Manufacturing method of integrated circuit device including thin film transistor

ABSTRACT

It is an object of the present invention to improve a factor which influences productivity such as variation caused by a characteristic defect of a circuit by thinning or production yield when an integrated circuit device in which a substrate is thinned is manufactured. A stopper layer is formed over one surface of a substrate, and an element is formed over the stopper layer, and then, the substrate is thinned from the other surface thereof. A method in which a substrate is ground or polished or a method in which the substrate is etched by chemical reaction is used as a method for thinning or removing the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an integrated circuit device and amanufacturing method thereof.

2. Description of the Related Art

In recent years, an element and an integrated circuit over a glasssubstrate are developed actively for using of a display such as an LCD,an organic EL, a photo sensor, a solar battery, or a photoelectricconversion element. Meanwhile, in an element and an integrated circuitusing a Si wafer, miniaturization and thinning of an IC chip areadvansed for use of a mobile phone. On either glass or a Si wafer,miniaturization and thinning are needed strongly. In addition, asemiconductor device which transmits and receives data (IC chip) hasbeen developed actively. Such a semiconductor device (IC chip) isreferred to as an RF tag, a wireless tag, an electronic tag, a wirelessprocessor, a wireless memory, or the like (for example, see Reference 1:Japanese Patent Laid-Open No. 2004-282050). An IC chip using a siliconsubstrate is mainly in pratical use, and a display or the like using aglass substrate is mainly in pratical use, and thinning of a substrateis required.

In addition, as well as being thinner, a flexible device such as an RFIDembedded in a paper, a display which can be wrapped around onto a pen, aforming sensor for a three-dimensional shape or a color sensor, a handroll PC, or clothes in which the design is changed by changing thecolor. Therefore, thinning is an important key.

When an element is formed by using a substrate which is made thinnerfrom the start, a substrate cassette becomes huge in height direction,and footprint of a device or a substrate is increased when warpage of asubstrate is considered. In addition, difficulty of handling, warpage bystress, or displacement in a process such as lithography or printingbecomes a problem. Therefore, a method in which an element ismanufactured and then a substrate is made thinner is used.

About thinning a substrate using grinding or polishing, planarity of thesubstrate is improved using by a polishing process using abrasive grainsafter grinding using abrasive grains, a film has been formed to bethinner. An abrasive grains having a lower Vickers hardness than asubstrate to be polished tend to be used for an artifice for increasingan evenness property. For example, cerium oxide (CeO₂) is used to aglass substrate or silicon oxide (SiO₂) is used for a silicon wafer, orthe like, and cerium oxide and silicon oxide have lower Vickers hardnessthan a substrate; however, only a portion which is attached firmly to anobject by chemical reaction can be polished selectively (see Reference1: Japanese Patent Laid-Open No. 2004-282050). Note that, here, thehardness is compared by using Vickers hardness; however, the hardness issometimes shown in a method other than Vickers hardness (Brinellhardness, Rockwell hardness, Knoop hardness, or the like).

In addition, there is a technique in which a glass substrate is removedby wet etching by chemical reaction (see Reference 2: Japanese PatentLaid-Open No. 2002-87844).

In addition, there is a technique in which an element formed over asubstrate is physically peeled from the substrate and transferred toanother substrate by controlling adhesion of a peeling layer formedunder an element (see Reference 3: Japanese Patent Laid-Open No.2004-214281).

When, in a semiconductor device such as an IC chip having an integratedcircuit device, a substrate over which an element is formed is madethinly by grinding and polishing, there is a limit of thinning by alimit of accuracy of a device and in-plane uniformity of polishing;therefore, it has been difficult to make the entire surface havethickness of 50 μm or less.

When warpage of in-plane of a substrate is considered, it is necessarythat a substrate is divided and made a small planar dimension, andwarpage of in-plane is reduced and processed in order to make asubstrate thinner with high yield, and it is a factor of throughputdegradation and cost increase. Therefore, even when a multiplicity ofsamples in which a minimum of a substrate residual film in a wholesurface is more than 50 μm in thickness is obtained, a minimum of asubstrate residual film in a whole surface becomes 50 μm more (100 μm or200 μm) when improving yield on a mass production is considered.

When a substrate in which an element is formed is made thinner by wetetching using a chemical solution, it has been very difficult to make asubstrate thinly to a thickness of 50 μm or less with high uniformityand high yield since there is a limit of thinning due to variationcaused in the etching rate of in-plane at a time of etching using achemical solution.

When a substrate is removed by a method using etching by chemicalreaction of Reference 2, it has been be a great limit that heattreatment at a temperature higher than a temperature of an allowabletemperature of an etching stopper layer formed under an element cannotbe performed.

When an element is separated from a substrate and is transposed toanother substrate by a method using controlling of adhesion in Reference3, there is a problem that a capacitance is generated between aseparation layer and an element and a properties before separating (inparticular, a high frequency property) is not evaluated accurately.

In addition, it is an advantage of this technique that a separationproperty can be controlled by heating; however, there is a demand forheat treatment at a more temperature at which a separation layer isseparated in a process or more.

In addition, in References 2 and 3, when heat process (lasercrystallization, laser activation, or the like) with visible light isperformed, the process margin has been reduced by optical reflection orheat absorption in an etching stopper layer or a separation layer.

In References 2 and 3, when a substrate which is transparent to light isused, self alignment by back light exposure is not able to be performedin a conductive separation layer.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention tomake an integrated device thin and flexible by making a substrate overwhich an element is formed thinner and removing the substrate.

In a case where an element such as a TFT is formed over a substrate andthe substrate over which an element is formed is made thin, if a part ofa layer where an element such as a TFT is formed as well as a substratedisappears is disappeared, abnormal properties are found.

Then, it is another object of the present invention to form an elementover a substrate and to control abnormal properties due to disappearanceof a part of an element which is caused when the substrate on which anelement is formed is made thin, thereby improving manufacturing yield.

Further, when a semiconductor substrate or a conductive substrate isused as a substrate over which an element is formed, the followingproblems occur. In the case of the semiconductor substrate, for example,when a Si wafer has a thickness of 10 μm or less, variations in thesubstrate thickness affects element properties. In addition, in the caseof a conductive substrate, variation of a substrate thickness affects anelement properties unless the substrate thickness becomes thin toapproximately “0” (removing the substrate almost completely). Therefore,even if a substrate is become thinly, it is difficult to controlvariation in the properties.

For countermeasures against a problem by such variation in a substratethickness, for example, there is a method in which an insulating film isformed over a semiconductor substrate or a conductive substrate and thenan element is formed as in an SOI substrate. This method is moreeffective to save electrical power, and high frequency properties becomegood. However, in this case, when a substrate is made thin to the limit,the capacitance properties are changed and property variation of anelement such as a TFT may increase due to variation of whether a Sisubstrate remains or not under an insulating film formed under anelement such as a TFT. Property variations are significant in the casewhere a part of a substrate disappears by being thinner. This alsoapplied to not only a case of using a Si wafer but also to a case ofusing another semiconductor substrate or a conductive substrate.

It is until another object of the present invention to form an elementover a substrate, and to improve factors which greatly affects massproduction such as property variations which are caused when a substrateover which an element is formed is made thin, or manufacturing yield inthe case of using a semiconductor substrate or a conductive substrate asa substrate.

In addition, since a silicon substrate is expensive, and the substrateis round and has a diameter of 12 inches (30 centimeters),mass-production of silicon substrates is difficult and it has been anobstacle to a reduction in costs. Thus, a plurality of IC chips can beformed at low cost by using a glass substrate; however, a glasssubstrate has a problem that there is more warpage than a Si wafer or aquartz substrate, and it has been difficult to make a whole surfacethinner uniformly. Since this problem is significant in a large-sizedsubstrate, it has been necessary to thin a substrate after dividing thesubstrate to a small dimensions substrate in order to make the substratethinner with high accuracy.

In view of the foregoing, it is a further object of the presentinvention to form an element which is inexpensive can be mass-produced,and has little variation even in the case of a thin film.

In the present invention, a stopper layer is formed over one surface ofa substrate, and an element is formed over the stopper layer, and thesubstrate is made thinly from the other surface of the substrate.

In the present invention, a stopper layer is formed over one surface ofa substrate, and an element is formed over the stopper layer, and asubstrate is removed.

In the present invention, a method in which a substrate is grinded orpolished is used for being a substrate thinly or removing a substrate,and a stopper layer is formed with a material having higher hardnessthan a substrate.

In the present invention, a method in which a substrate is etched bychemical reaction is used for making a substrate thin or removing asubstrate, and a stopper layer is formed with a material which isresistant to an etchant used when etching by chemical reaction isperformed.

In addition, in the above configuration, a stopper layer is formed witha material which mainly contains diamond like carbon.

In each of the above structures, a layer (buffer layer) for improvingadhesion between a substrate and a stopper layer is formed between asubstrate and a stopper layer.

In each of the above structures, a layer (buffer layer) to improveadhesion between a stopper layer and an element is formed between astopper layer and an element.

In the present invention, a layer (DLC layer) which mainly containsdiamond like carbon is formed over one surface of a substrate, and anelement is formed over the layer which mainly contains diamond likecarbon, and the substrate is removed by controlling adhesion between aDLC layer and the substrate.

In the present invention, a method in which a substrate is separated bycontrolling adhesion between a DLC layer and a substrate is used as amethod in which a substrate is removed.

In the present invention, a substrate is made thinner or removed bycombining plural methods among a method in which a substrate is grindedor polished, a method in which a substrate is etched by chemicalreaction, a method in which a substrate is separated by controllingadhesion between a DLC layer and a substrate.

The thickness of the thinned substrate is 100 μm or less, preferably, 20μm or less, more preferably, 10 μm or less.

According to the present invention, since a substrate can be madethinner or be removed, an integrated circuit device thinner than beforecan be provided.

When a grinding method or a polishing method is used for making asubstrate thinner or removing a substrate, due to the presence of astopper layer, a layer formed above the stopper layer can be preventedfrom being grinded or polished. Therefore, an integrated circuit devicethinner than before can be provided.

When an etching method by chemical reaction is used for making asubstrate thinner or removing a substrate, due to the presence of astopper layer, a layer formed above the stopper layer can be preventedfrom being etched. Therefore, an integrated circuit device thinner thanbefore can be provided.

In particular, when diamond like carbon (DLC) is used as a stopperlayer, conditions for heating an element formed thereover is not limiteddue to the heat resistance of DLC.

When a separating method by controlling adhesion of DLC is used formaking a substrate thinner or removing a substrate, a substrate can beremoved due to the presence of a DLC layer. Therefore, an integratedcircuit device thinner than before can be provided. In addition, heattreatment can be performed without significantly changing the adhesiondue to heat resistance of DLC. Therefore, there is an advantage thatprocess restructions are reduced in manufacturing a thin integratedcircuit device.

By using an insulating substrate, effects of variations in the thicknessof a thinned substrate, or variations in element properties orcapacitance due to a residue of a substrate can be prevented.

Even when an element is formed over a semiconductor substrate such as anSi wafer or an SOI substrate or a conductive substrate, by removing asubstrate using the present invention, effects of variations in thethickness of a thinned substrate (in the case of a substarate is 10 μmthickness or less), or variations in an element properties orcapacitance due to a residue of a substrate (in the case where even apart of a substrate is 0 μm) can be prevented.

The present invention can use a substrate of which size is not limitedsuch as a glass substrate. In the present invention, the price of an ICchip is reduced compared with the case of using a silicon substrate andmass-production can be performed.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1A to 1C are diagrams describing Embodiment Mode 1;

FIGS. 2A to 2C are diagrams describing Embodiment Mode 1;

FIGS. 3A to 3C are diagrams describing Embodiment Mode 1;

FIGS. 4A and 4B are diagrams describing Embodiment Mode 1;

FIGS. 5A and 5B are diagrams describing Embodiment Mode 1;

FIGS. 6A and 6B are diagrams describing Embodiment Mode 1;

FIGS. 7A to 7C are diagrams describing Embodiment Mode 2;

FIGS. 8A to 8C are diagrams describing Embodiment Mode 2;

FIGS. 9A and 9B are diagrams describing Embodiment Mode 2;

FIG. 10 is a diagram describing Embodiment Mode 2;

FIGS. 11A to 11C are diagrams describing Embodiment Mode 3;

FIGS. 12A to 12C are diagrams describing Embodiment Mode 3;

FIGS. 13A to 13C are diagrams describing Embodiment Mode 3;

FIGS. 14A to 14C are diagrams describing Embodiment Mode 3;

FIGS. 15A to 15C are diagrams describing Embodiment Mode 4;

FIGS. 16A to 16C are diagrams describing Embodiment Mode 4;

FIGS. 17A to 17C are diagrams describing Embodiment Mode 4;

FIGS. 18A to 18C are diagrams describing Embodiment Mode 4;

FIG. 19 is a diagram describing Embodiment Mode 4;

FIGS. 20A to 20C are diagrams describing Embodiment Mode 4;

FIGS. 21A to 21C are diagrams describing Embodiment Mode 4;

FIGS. 22A to 22C are diagrams describing Embodiment Mode 4;

FIGS. 23A and 23B are diagrams describing Embodiment Mode 4;

FIGS. 24A and 24B are diagrams describing Embodiment Mode 1;

FIGS. 25A to 25E are diagrams describing Embodiment 1; and

FIGS. 26A and 26B are diagrams describing Embodiment 1.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiment modes of the present invention will be describedin detail with reference to the accompanying drawings. However, thepresent invention is not limited to the description below, and it iseasily understood by those skilled in the art that modes and details canbe modified in various ways without departing from the spirit and thescope of the present invention. Therefore, the present invention shouldnot be understood as being limited to the description of the embodimentmodes to be given below. Note that in the structures of the presentinvention described below, the reference numerals indicating the sameare used in common in the drawings.

Embodiment Mode 1

This embodiment mode is described using FIGS. 1A to 6B. In thisembodiment mode, an example in which a layer which mainly containsdiamond like carbon is formed over a substrate as a stopper layer in acase that a substrate is made thinly by grinding and polishing isdescribed.

A layer (DLC layer) which mainly contains DLC (diamond like carbon) isformed over a first substrate 100. It is preferable that a layer forimproving adhesion (buffer layer) is formed between the first substrate100 and the DLC layer, and between the DLC layer and a layer formed overthe DLC layer. In this example, a layer for improving adhesion (bufferlayer) 101, a DLC layer 102, and a layer for improving adhesion (bufferlayer) 103 are formed sequentially over one surface of the firstsubstrate 100 (see FIG. 1A). In this particular example, before forminga DLC layer 102, a layer which mainly contains DLC which contains Si ata concentration of 1 to 20% is formed as the layer for improvingadhesion (buffer layer) 101, and after film formation of the DLC layer102, a layer which mainly contains DLC which contains Si at aconcentration of 1 to 20% is formed as the layer for improving adhesion(buffer layer) 103.

In FIG. 1A, the layers for improving adhesion (buffer layers) 101 and103 are provided; however, if there is no particular problem in adhesionbetween the first substrate 100 and the DLC layer, or the DLC layer anda layer formed over the DLC layer, the layer for improving adhesion(buffer layer) 101 or the layer for improving adhesion (buffer layer)103 does not have to be formed necessarily.

The DLC layer 102 is formed by a PECVD method using gas including carbonsuch as CH₄ gas, or by coating by implanting a carbon ions.

The layers for improving adhesion (buffer layers) 101 and 103 are formedby streaming gas including Si such as SiH₄ gas with gas including carbonsuch as CH₄ gas and using a PECVD method, or streaming gas including Sisuch as SiH₄ gas at the same time when coating is performed byimplanting carbon ions. At this time, gas including nitrogen such as N₂gas or NH₃ gas is streamed instead of SiH₄, so that layers which mainlycontains DLC including nitrogen may be formed as the layers forimproving adhesion (buffer layers) 101 and 103 instead.

As a manufacturing method of the layer for improving adhesion (bufferlayer) 101, a surface of the first substrate may be nitrided byperforming high-density plasma treatment using a gas mainly containingnitrogen such as N₂ gas or NH₃ gas to the first substrate, or thesurface or vicinity of the first substrate may be nitrided by doping orion implanting nitrogen ions to the substrate. In addition, the layerfor improving adhesion (buffer layer) 101 may be formed as a DLC filmincluding nitrogen by forming a DLC film and performing high-densityplasma treatment using gas which mainly contains nitrogen such as N₂ gasor NH₃ gas to be nitrided the DLC film or a nitrogen ion is doped orperformed ion implantation to the DLC film to be nitrided the DLC film.A layer which has good adhesion with DLC may be formed such as a WC(tungsten carbide) film, a BCN (boron carbonitride) film, a BN (boronnitride) film, a DLC film added with SiC (silicon carbide) or Ti as thelayer for improving adhesion (buffer layer) 101.

As a forming method of the layer for improving adhesion (buffer layer)103, a surface of the DLC layer 102 may be nitrided by performinghigh-density plasma treatment using a gas mainly containing nitrogensuch as N₂ gas or NH₃ gas to the DLC layer 102, or the the DLC layer 102may be nitrided by doping or ion planting nitrogen ions, and then theDLC film including nitrogen may be formed. A layer which has goodadhesion with DLC may be formed such as a WC (tungsten carbide) film, aBCN (boron carbonitride) film, a BN (boron nitride) film, a DLC filmadded SiC (silicon carbide) or Ti as the layer for improving adhesion(buffer layer) 103.

In this specification, the “high-density plasma treatment” indicatestreatment in which an electron density of plasma is 1×10¹¹ cm⁻³ or moreand 1×10¹³ cm⁻³ or less, and an electron temperature of plasma is 0.5 eVor more and 1.5 eV or less. Since the electron temperature in thevicinity of an object formed over a substrate is low while the electrondensity of plasma is high, damage due to plasma of the substrate can beprevented. Further, since the electron density of plasma is high as1×10¹¹ cm⁻³ or more, a dense film with a uniform thickness, which isformed of oxide generated by oxidation treatment, can be formed.Further, the electron temperature of plasma is low as 1.5 eV or less,and therefore, oxidation treatment can be performed at a lowertemperature as compared with normal plasma treatment or thermaloxidation. For example, even when plasma treatment is performed at atemperature lower than a strain point of the glass substrate by about100° C. or more (for example, 250 to 550° C.), plasma oxidationtreatment can be sufficiently performed. Note that, as a power supplyfrequency for generating plasma, a microwave (2.45 GHz) is used.Further, potential of plasma is low as 5 V or less so that excessivedissociation of molecules of a raw material can be suppressed.

As the first substrate 100, any one of a glass substrate, a quartzsubstrate, an Si substrate, a semiconductor substrate, a plasticsubstrate, an acrylic substrate (a kind of a plastic substrate), a metalsubstrate, or the like can be used as long as it can endure maximumtemperature in a manufacturing process of an element. Among thesesubstrates, a glass substrate or the like can easily be made to have 1meter or more on a side, in addition, the shape can be made to a desiredshape such as quadrangle or round shape. Thus, for example, if asubstrate having 1 meter or more on a side is used, productivity can beimproved significantly. Such a characteristic is a great advantage ascompared to a case of obtaining IC chips from a circular Si substrate.

Next, a layer 104 including an element is formed over the layer forimproving adhesion (buffer layer) 103 (see FIG. 1B). For example, thislayer may have a wire, capacity, an inductor (antenna) or the like andthe combination thereof instead of a unit circuit such as a TFT circuit.In this particular example, a TFT circuit 105 is formed in the layer 104including an element. In this figure, the TFT circuit 105 has anN-channel transistor 106 and a P-channel transistor 107. Each of theN-channel transistor 106 and the P-channel transistor 107 has asemiconductor film 108, a gate insulating film 109, a gate electrode110, an interlayer insulating film 111, and a source or drain electrode135.

In this example, the TFT circuit 105 includes at least a plurality ofinsulating films and a semiconductor film and a conductive filmcomposing a plurality of elements. Specifically, the TFT circuit 105includes a plurarity of elements (in this case, the N-channel transistor106 and the P-channel transistor 107), an interlayer insulating film 111covering a plurarity of elements, and a first conductive layer 135(source or drain electrode) which contacts the interlayer insulatingfilm 111 and is connected to a plurality of elements.

In this example, a terminal for external connection is formed and anintegrated circuit which can be combined with other substrate is formed.Therefore, an insulating film 112 is formed over the layer 104 includingan element, and an opening portion is formed in the insulating film 112.Next, an electrode 113 enabling contact with the TFT circuit 105 isformed (see FIG. 1C).

An example of a manufacturing method of the layer 104 including anelement is described in detail, hereinafter.

First, an amorphous semiconductor film is formed over the layer forimproving adhesion 103. The amorphous semiconductor film is formed bysputtering or various types of CVD such as plasma CVD. Subsequently, theamorphous semiconductor film is crystallized to form a crystallinesemiconductor film. As a crystallization method, laser crystallization,thermal crystallization using RTA or an annealing furnace, thermalcrystallization using a metal element for promoting crystallization,thermal crystallization using a metal element for promotingcrystallization with laser crystallization, or the like can be used.Thereafter, the thus obtained crystalline semiconductor film ispatterned into a desired shape to form crystalline semiconductor film108.

An example of steps of manufacturing the crystalline semiconductor filmswill be briefly described below. As a method for crystallizing theamorphous semiconductor films, laser crystallization, thermalcrystallization using RTA or an annealing furnace, thermalcrystallization using a metal element for promoting crystallization,thermal crystallization using a metal element for promotingcrystallization with laser crystallization, or the like can be given.Further, as other crystallization method, crystallization may beperformed by generating thermal plasma by applying DC bias and makingthe thermal plasma affect a semiconductor film.

When employing laser crystallization, a continuous wave laser beam (CWlaser beam) or a pulsed laser beam (pulse laser beam) can be used. As ausable laser beam, a beam emitted from one or plural kinds of a gaslaser such as an Ar laser, a Kr laser, or an excimer laser; a laserusing, as a medium, single crystalline YAG, YVO₄, forsterite (Mg₂SiO₄),YAlO₃, or GdVO₄ or polycrystalline (ceramic) YAG, Y₂O₃, YVO₄, YAlO₃, orGdVO₄ doped with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as adopant; a glass laser; a ruby laser; an alexandrite laser; a Ti:sapphire laser; a copper vapor laser; and a gold vapor laser, can beused. An object is irradiated with a laser beam having a fundamentalwave of such lasers or a second to a fourth harmonic of a fundamentalwave to obtain a crystal with a large grain size. For instance, thesecond harmonic (532 nm) or the third harmonic (355 nm) of an Nd: YVO₄laser (fundamental wave of 1,064 nm) can be used. In this case, thepower density of about 0.01 to 100 MW/cm² (preferably, 0.1 to 10 MW/cm²)is required for a laser. The scanning rate is approximately set to beabout 10 to 2,000 cm/sec to irradiate the semiconductor film.

Note that each laser using, as a medium, single crystalline YAG, YVO₄,forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄ or polycrystalline (ceramic) YAG,Y₂O₃, YVO₄, YAlO₃, or GdVO₄ doped with one or more of Nd, Yb, Cr, Ti,Ho, Er, Tm, and Ta as a dopant; an Ar ion laser; and a Ti: sapphirelaser, can continuously oscillate. Further, pulse oscillation thereofcan be performed with an oscillation frequency of 10 MHz or more bycarrying out Q switch operation or mode synchronization. When a laserbeam is oscillated with an oscillation frequency of 10 MHz or more, asemiconductor film is irradiated with a next pulse during a period wherethe semiconductor film is melted by the laser beam and then issolidified. Therefore, differing from a case of using a pulse laser witha low oscillation frequency, a solid-liquid interface can becontinuously moved in the semiconductor film so that crystal grains,which continuously grow toward a scanning direction, can be obtained.

When the amorphous semiconductor film is crystallized by using acontinuous wave laser or a laser beam which oscillates at a frequency of10 MHz or more as described above, a surface of the crystallizedsemiconductor film can be planarized. As a result, a gate insulatingfilm 109, which will be formed later, can be formed thinly. In addition,this contributes to improve pressure resistance of the gate insulatingfilm 109.

When ceramic (polycrystal) is used as a medium, the medium can be formedto have a free shape for a short time at low cost. When using a singlecrystal, a columnar medium with several mm in diameter and several tensof mm in length is usually used. In the case of using the ceramic, amedium bigger than the case of using the single crystal can be formed.

A concentration of a dopant such as Nd or Yb in a medium, which directlycontributes to light emission, cannot be changed largely in both casesof the single crystal and the polycrystal, and therefore, there is alimitation in improvement in output of a laser by increasing theconcentration of the dopant to some extent. However, in the case of theceramic, the size of a medium can be significantly increased as comparedwith the case of the single crystal, and therefore, drastic improvementin output of a laser can be expected.

Further, in the case of the ceramic, a medium with a parallelepipedshape or a rectangular parallelepiped shape can be easily formed. In acase of using a medium having such a shape, when oscillated light ismade travel in a zig-zag manner inside the medium, a path of theoscillated light can be made long. Therefore, amplitude is increased anda laser beam can be oscillated at high output. Furthermore, a crosssection of a laser beam emitted from a medium having such a shape has aquadrangular shape, and therefore, as compared with a laser beam with acircular shape, the laser beam with the quadrangular shape in crosssection have an advantage to be shaped into a linear beam. By shaping alaser beam emitted in the above described manner using an opticalsystem, a linear beam with 1 mm or less in length of a short side andseveral mm to several m in length of a long side can be easily obtained.In addition, when a medium is uniformly irradiated with excited light, alinear beam is emitted with a uniform energy distribution in a long sidedirection.

When a semiconductor film is irradiated with this linear beam, thesemiconductor film can be uniformly annealed. In a case where uniformannealing is required from one end to the other end of the linear beam,an ingenuity in which slits are provided in both ends of the linear beamso as to shield an attenuated portion of energy from light, or the likemay be performed.

When a semiconductor film is annealed by using the thus obtained linearbeam with uniform intensity and a semiconductor device is manufacturedby using this semiconductor film, a characteristic of the semiconductordevice can be made favorable and uniform.

As thermal crystallization using a metal element for promotingcrystallization, an example of a specific method will be given. Afterkeeping a solution containing nickel, which is a metal element forpromoting crystallization, over an amorphous semiconductor film, theamorphous semiconductor film is subjected to dehydrogenation treatment(500° C. for one hour) and thermal crystallization treatment (550° C.for four hours) so as to form a crystalline semiconductor film.Thereafter, the crystalline semiconductor film is irradiated with alaser beam if required, and then, the crystalline semiconductor film ispatterned by photolithography to form the crystalline semiconductor film108.

The thermal crystallization using a metal element for promotingcrystallization has advantages of being capable of crystallizing anamorphous semiconductor film at a low temperature for a short time andaligning a direction of crystals; however, the thermal crystallizationhas drawbacks that off current is increased due to a remnant of themetal element in the crystalline semiconductor film and characteristicsof the crystalline semiconductor film are not stabilized. Therefore, itis preferable to form an amorphous semiconductor film serving as agettering site over the crystalline semiconductor film. Since theamorphous semiconductor film, which becomes the gettering site, isnecessary to contain an impurity element such as phosphorus or argon,the amorphous semiconductor film is preferably formed by sputtering bywhich the amorphous semiconductor film can contain argon at a highconcentration. Thereafter, heat treatment (RTA, thermal annealing usingan annealing furnace, or the like) is performed to disperse a metalelement in the amorphous semiconductor film. Subsequently, the amorphoussemiconductor film containing the metal element is removed. By carryingout such the gettering process, the amount of the metal elementcontained in the crystalline semiconductor film can be reduced or themetal element can be removed.

Next, a gate insulating film 109 is formed to cover the crystallinesemiconductor film 108. The gate insulating film 109 is formed by usinga single layer or a stacked layer containing silicon oxide or siliconnitride by sputtering or various types of CVD such as plasma CVD.Specifically, the gate insulating film 109 is formed by using a singlelayer of a film containing silicon oxide, a film containing siliconoxynitride, or a film containing silicon nitride oxide, or byappropriately stacking these films. Alternatively, the semiconductorfilm 108 may be subjected to the above described high-density plasmatreatment under an atmosphere containing oxygen, nitrogen, or both ofoxygen and nitrogen to oxidize or nitride each surface of thesemiconductor film 108 so as to form the gate insulating film. The gateinsulating film formed by the high-density plasma treatment has superioruniformity in film thickness and film quality as compared with a filmformed by CVD or sputtering. In addition, a dense film can be formed asthe gate insulating film by the high-density plasma treatment. As anatmosphere containing oxygen, a mixed gas of oxygen (O₂), nitrogendioxide (NO₂) or dinitrogen monoxide (N₂O), and a rare gas; or a mixedgas of oxygen (O₂), nitrogen dioxide (NO₂) or dinitrogen monoxide (N₂O),a rare gas, and hydrogen (H₂); can be used. Further, as an atmospherecontaining nitrogen, a mixed gas of nitrogen (N₂) or ammonia (NH₃) and arare gas; or a mixed gas of nitrogen (N₂) or ammonia (NH₃), a rare gas,and hydrogen (H₂); can be used. Each surface of the semiconductor film108 can be oxidized or nitrided by oxygen radical (which contains OHradical in some cases) or nitrogen radical (which contains NH radical insome cases) generated by high-density plasma.

When the gate insulating film 109 is formed by the high-density plasmatreatment, an insulating film with a thickness of 1 to 20 nm, andtypically, 5 to 10 nm, is formed over the semiconductor film 108. Areaction in this case is a solid-phase reaction, and therefore,interface state density between the insulating film and thesemiconductor film 108 can be extremely reduced. Further, since thesemiconductor film 108 can be directly oxidized or nitrided, variationsin thickness of the gate insulating film 109 to be suppressedsignificantly and ideally. Furthermore, since strong oxidation is notgenerated in a crystal grain boundary of crystalline silicon, anextremely preferable state is made. That is, when each surface of thecrystalline semiconductor films is subjected to solid-phase oxidation bythe high-density plasma treatment shown here, an insulating film withlow interface state density and good uniformity can be formed withoutgenerating abnormal oxidation reaction in a crystal grain boundary.

Note that, as the gate insulating film 109, only an insulating filmformed through the high-density plasma treatment may be used.Alternatively, the insulating film formed through the high-densityplasma treatment and another insulating film formed using silicon oxide,silicon nitride containing oxygen, or silicon oxide containing nitrogenby CVD utilizing plasma or a thermal reaction may be stacked to form thegate insulating film. In FIG. 1B, the structure that a laminatedinsulating film by CVD is had as well as the insulating film formed byhigh-density plasma treatment. In either case, when a transistor isformed to have a gate insulating film which partly or entirely includesan insulating film formed by high-density plasma, variations incharacteristics can be reduced.

Further, the crystalline semiconductor films formed by crystallizing theamorphous semiconductor film by irradiation of a continuous wave laserbeam or a laser beam oscillated at a frequency of 10 MHz or more whilescanning the amorphous semiconductor film with the laser beam in onedirection, have a characteristic that crystals grow in a scanningdirection of the laser beam. Therefore, when a transistor is disposedsuch that the scanning direction corresponds to a channel lengthdirection (a direction of flowing carries when a channel formationregion is formed), and the gate insulating film 109 formed by thehigh-density plasma treatment is combined with the transistor, atransistor with less variations in characteristics and high electronfield-effect mobility can be obtained.

Next, the gate electrode 110 is formed over the gate insulating film109. The gate electrode 110 may be formed by sputtering or various typesof CVD such as plasma CVD. In addition, the gate electrode 110 can beformed by using an element selected from tantalum (Ta), tungsten (W),titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium(Cr), niobium (Nb), and the like; or an alloy material or a compoundmaterial mainly containing these elements. Further, the gate electrode110 can be formed by using a semiconductor material typified bypolycrystalline silicon doped with an impurity element such asphosphorus.

Next, impurity elements are selectively added to the semiconductor film108 by ion doping or ion implantation to form N-channel transistor 106and P-channel transistor 107. Note that in FIG. 1B, an LDD region (a lowconcentration impurity region) is formed using an insulating film (asidewall) in contact with a side surface of each gate electrode 110 ineach of the N-channel transistor 106. As an impurity element impartingN-type used for forming the N-channel transistors 106, an elementbelonging to Group 15 of the periodic table may be used, and forexample, phosphorus (P) or arsenic (As) is used. Further, as an impurityelement imparting P-type used for forming the P-channel thin filmtransistor 107, an element belonging to Group 13 may be used, and forexample, boron (B) is used.

After completing the N-channel transistor 106 and the P-type transistor107 through the above described steps, heat treatment for recoveringcrystallinity of the semiconductor films or activating the impurityelements added to the semiconductor films, may be performed. Further,after performing the heat treatment, the exposed gate insulating film109 may be subjected to high-density plasma treatment under anatmosphere containing hydrogen so that a surface of the gate insulatingfilm 109 may contain hydrogen. This is because the hydrogen can beutilized when performing a step of hydrogenating the semiconductor filmslater. Further, by performing high-density plasma treatment under anatmosphere containing hydrogen while heating the substrate at 350 to450° C., hydrogenation of the semiconductor films can be performed.Further, as the atmosphere containing hydrogen, a mixed gas of hydrogen(H₂) or ammonia (NH₃) and a rare gas (for example, argon (Ar)) can beused. When a mixed gas of ammonia (NH₃) and a rare gas (for example,argon (Ar)) is used as the atmosphere containing hydrogen, the surfaceof the gate insulating film 109 can be hydrogenated and nitrided at thesame time.

Then, the interlayer insulating film 111 is formed to cover theplurality of transistors. The interlayer insulating film 111 is formedusing a single layer or a stacked layer made from an inorganic materialsuch as silicon oxide or silicon nitride; an organic material such aspolyimide, polyamide, benzocychlobutene, acrylic, or epoxy; siloxane; orthe like, by an SOG technique, a droplet discharing method, or the like.In this specification, siloxane has a skeleton structure includingsilicon (Si)-oxygen (O) bonds and an organic group containing at leasthydrogen (for example, an alkyl group, aromatic hydrocarbon, or thelike) is used as a substituent. Further, as the substituent, a fluorogroup may be used, or both of an organic group containing at leasthydrogen and a fluoro group may be used. For example, in a case wherethe interlayer insulating film 111 has a three layer structure, a filmmainly containing silicon oxide may be formed as a first insulatingfilm, a film mainly containing a resin may be formed as a secondinsulating film, and a film mainly containing silicon nitride may beformed as a third insulating film. Further, in a case where theinterlayer insulating film 111 has a single layer structure, a siliconnitride film or a silicon nitride film containing oxygen may be formed.In this case, it is preferable that by performing high-density plasmatreatment under an atmosphere containing hydrogen with respect to thesilicon nitride film or the silicon nitride film containing oxygen,hydrogen be contained in a surface of the silicon nitride film or thesilicon nitride film containing oxygen. This is because when performinga hydrogenation step of the semiconductor film 108 later, this hydrogencan be utilized. Further, by performing high-density plasma treatmentunder an atmosphere containing hydrogen while heating the substrate at350 to 450° C., hydrogenation of the semiconductor films can beperformed. Note that, as the atmosphere containing hydrogen, a mixed gasof hydrogen (H₂) or ammonia (NH₃) and a rare gas (for example, argon(Ar)) can be used. When a mixed gas of ammonia (NH₃) and a rare gas (forexample, argon (Ar)) is used as the atmosphere containing hydrogen, thesurface of the gate insulating film 109 can be hydrogenated and nitridedat the same time.

Note that, prior to forming the interlayer insulating film 111, heattreatment for recovering crystallinity of the semiconductor films,activating the impurity elements added to the semiconductor films, orhydrogenating the semiconductor films, is preferably performed. The heattreatment preferably employs thermal annealing, laser annealing, RTA, orthe like. For example, in order to activate the impurity elements,thermal annealing at 500° C. or more is preferably performed. Further,in order to hydrogenate the semiconductor films, thermal annealing at350 to 450° C. may be performed.

Next, the interlayer insulating film 111 and the gate insulating film109 are etched by photolithography to form contact holes through whichthe semiconductor film 108 are exposed. Subsequently, a conductive filmis formed to fill the contact holes. The conductive film is patterned toform source or drain electrodes 135.

The source or drain electrodes 135 are formed by using a conductive filmmainly containing aluminum (Al) by sputtering, various types of CVD suchas plasma CVD, or the like. The conductive film mainly containingaluminum (Al) corresponds to a material mainly containing aluminum,which also contains nickel, or an alloy material mainly containingaluminum, which also contains nickel and one or both of carbon andsilicon, for example. Since the conductive film mainly containingaluminum generally has a drawback of a poor heat resistance property, anupper surface and a lower surface of the conductive film mainlycontaining aluminum are preferably covered with barrier films. Thebarrier films indicate films having a function of suppressing heroic ofthe conductive film mainly containing aluminum or improving a heatresistance property. As a material having such a function, chromium,tantalum, tungsten, molybdenum, titanium, silicon, and nickel, ornitride of these elements can be given. As an example of a structure ofeach of the source or drain electrodes 135, a structure in which atitanium film, an aluminum film, and another titanium film aresequentially stacked from a substrate side, can be given. Since titaniumis an element having a high reducing property, even when a thin oxidefilm is naturally formed on the crystalline semiconductor film, theoxide film naturally formed can be reduced by the titanium so that thetitanium film can be well-contacted to the crystalline semiconductorfilm. Further, the titanium film formed between the crystallinesemiconductor film and the aluminum film, is preferably subjected tohigh-density plasma treatment under an atmosphere containing nitrogen tonitride a surface of the titanium film. In a condition of thehigh-density plasma treatment, electron density of plasma is 1×10¹¹ cm⁻³or more and 1×10¹³ cm⁻³ or less, and an electron temperature of plasmais 0.5 eV or more and 1.5 eV or less. As the atmosphere containingnitrogen, a mixed gas of N₂ or NH₃ and a rare gas, or a mixed gas of N₂or NH₃, a rare gas, and H₂ can be used. Nitriding the surface of thetitanium film makes it possible to prevent alloying of titanium andaluminum and prevent aluminum from dispersing in the crystallinesemiconductor film through the titanium film in a step of heat treatmentor the like, which will be performed later. Note that an example ofsandwiching the aluminum film with the titanium films is described here,and this is the same for a case of using chromium films, tungsten films,or the like instead of the titanium films. More preferably, formation ofthe titanium film, nitriding treatment of the surface of the titaniumfilm, formation of the aluminum film, and formation of another titaniumfilm are successively carried out by using a multi-chamber apparatuswithout exposing these films to atmospheric air.

According to the above described steps, the layer 104 including anelement is formed.

Next, a second substrate 115 is bonded over the insulating film 112 andthe electrode 113 by using a first adhesive 114 (see FIG. 2A). Thesecond substrate 115 is a substrate for keeping flatness of the layer104 including an element and for protecting flatness of the layer 104including an element. Adhesion of the first adhesive 114 is strong in anomal state, and it is preferable that the first adhesive 114 has aproperty such that the adhesion becomes weak by light irradiation orheating. Specifically, a UV peelable adhesive of which adhesion becomesweak by irradiation with ultraviolet radiation, or a heat peelableadhesive of which adhesion becomes weak by heating may be used. In thisexample, a UV peelable adhesive is used as the first adhesive 114.

In this example, the second substrate 115 is composed of only asubstrate; however, an element or a plurality of elements may be formedover the second substrate 115. An element corresponds to a thin filmtransistor, a capacitor element, a resistance element, an inductor, adiode, or the like.

In grinding, polishing, or the like, an elastic substrate (for example,an expand film, or the like) is further bonded over the second substrate115, and a space between separated substrates is made wider by expandingthe elastic substrate after separating the second substrate 115, and thesubstrate can be handled easily. Accordingly, such a method can beemployed. Since an object of this example is to make the first substratethinner by using flatness of the second substrate; therefore, such amethod is not used.

Next, a surface opposite to one surface (a surface over which the TFTcircuit 105 is formed) of the first substrate 100 is ground or polishedby a grinding means or a polishing means 116 (see FIG. 2B). In thisexample, grinding is performed until the thickness of the firstsubstrate 100 becomes 100 μm or less. Then, polishing is performed untilthe thickness of the first substrate 100 becomes 20 μm or less. At thistime, grinding and polishing may be performed until the first substrate100 almost disappears.

Here, for example, there is silicon, glass, quartz, or the like as amaterial used as a substrate. Vickers hardness of silicon is about 1000kg/mm², and Vickers hardness of glass, quartz, or the like is about 600to 900 kg/mm². In addition, as abrasive grains used in a polishingprocess, cerium oxide (CeO₂) is used when a glass substrate is polished,silicon oxide (SiO₂) is used when a silicon wafer is polished, alumina(Al₂O₃) is used when a metal substrate is polished. Vickers hardness ofalumina (Al₂O₃) is about 2200 kg/mm², Vickers hardness of silicon isabout 1000 kg/mm², Vickers hardness of silicon oxide (SiO₂) or the likeis about 600 to 900 kg/mm², and Vickers hardness of cerium oxide (CeO₂)is lower than that of glass. Meanwhile, Vickers hardness of diamond likecarbon is about 2500 to 4000 kg/mm², which is higher than a materialused as a substrate. Therefore, a layer formed over the diamond likecarbon layer can be prevented from ground or polished by forming the DLClayer 102 between the first substrate 100 and the layer 104 including anelement. In addition, since DLC has not only high hardness but also goodsurface flatness and a lower coefficient of friction, it serves as ahigh functionality stopper layer. Note that, here, hardness is comparedusing Vickers hardness; however, the hardness is sometimes may be shownin a method other than Vickers hardness (Brinell hardness, Rockwellhardness, Knoop hardness, or the like).

Here, an example in which the first substrate 100 is ground until thethickness becomes 100 μm or less, and then, the first substrate 100 ispolished until the thickness becomes 20 μm or less is shown; however,grinding or polishing may be at least until the thickness of the firstsubstrate 100 becomes thin to be easily separated. If the substrate ismade thinner than before, the thickness should be 100 μm or less. Sincethe substrate becomes strong against bending when the thickness becomes20 μm or less, the substrate can be made not only thin but also flexible(an advantage which can be assumed a thing having flexibility), which ispreferable. In a case of using an insulating substrate, since anadvantage of thinning is significant when the thickness of the substrateis 10 μm or less where dependency of variations in the thickness isconsiderable in a semiconductor substrate or a conductive substrate, itis more preferable. In the semiconductor substrate or the conductivesubstrate, it is preferable to remove the substrate completely; however,when an element is formed in the substrate, the thickness of thesubstrate is in the range of 10 to 100 μm.

In this grinding process, the surface of the first substrate 100 isground or polished by rotating one or both of a stage over which thefirst substrate is fixed and the grinding means or the polishing means116. At this time, not only the first substrate 100 but also the secondsubstrate 115 may be ground or polished at the same time. This exampleshows a case where only the first substrate 100 is ground or polished.

The grinding means or the polishing means 116 is, for example, agrinding stone used for grinding or loose abrasive process graintreatment used for polishing. Thereafter, cleaning may be performed asnecessary in order to remove dust generated by a grinding or a polishingprocess.

After this process is finished, the first substrate 100 may be removedentirely (see FIG. 2C). FIG. 2C shows a case that the first substrate100 is removed entirely.

In addition, when the first substrate is thinned by using a grindingmeans or a polishing means, the first substrate 100 may be peeled offfrom the layer for improving adhesion (buffer layer) 101 to be removedby shock and vibration of grinding or polishing. Controlling of theadhesion is described in detail in Embodiment Mode 3.

In this example, the electrode 113 electrically connected with the TFTcircuit 105 is formed on the second substrate 115 side. In addition, theelectrode can be electrically connected with the TFT circuit 105 on thefirst substrate 100 side, and mounted on another substrate (for example,a substrate on which an antenna is formed, or the like). In this case,the third substrate below may not necessarily be provided.

A method for forming an electrode electrically connected with the TFTcircuit 105 on the first substrate 100 side, in other words, a surfaceover which the DLC layer 102 is formed is as follows.

When the first substrate 100 remains, the first substrate 100, the layerwhich mainly contains DLC (the layer for improving adhesion (bufferlayer) 101, the DLC layer 102, and the layer for improving adhesion(buffer layer) 103), the gate insulating film 109, the interlayerinsulating film 111, and an opening is formed in the insulating film 112by using UV laser, and a contact hole which reaches the electrode 113 isformed. An electrode for making a contact through this contact hole isformed. A mounting process follows after that. After mounting, thesecond substrate 115 is peeled off.

When the first substrate 100 is removed completely, the first substrate100, the layer which mainly contains DLC (the layer for improvingadhesion (buffer layer) 101, the DLC layer 102, and the layer forimproving adhesion (buffer layer) 103), the gate insulating film 109,the interlayer insulating film 111, and an opening is formed in theinsulating film 112 by using UV laser, and a contact hole which reachesthe electrode 113 is formed. An electrode to take a contact through thiscontact hole is formed. A mounting process follows after that. Aftermounting, the second substrate 115 is peeled off.

In this example, the integrated circuit is mounted on the secondsubstrate 115 side. If the second substrate 115 is peeled off here, thelayer 104 including an element is curled by stress, and a problem occursin the later mounting or handling. A third substrate 117 is bonded fromthe side opposite to the second substrate 115 by using the secondadhesive 148 in order to prevent the above problem. In other words, whenthe first substrate 100 remains, the third substrate 117 is bonded tothe first substrate 100 by using the second adhesive 148. When the firstsubstrate 100 is removed, and the layer for improving adhesion (bufferlayer) 101 is exposed in a surface, the third substrate 117 is bonded tothe layer for improving adhesion (buffer layer) 101 by using the secondadhesive 148. When the first substrate 100 and the layer for improvingadhesion (buffer layer) 101 are removed and the DLC layer 102 is exposedin a surface, the third substrate 117 is bonded to the DLC layer 102 byusing the second adhesive 148 (see FIG. 3A). In this example, the thirdsubstrate 117 is bonded to the layer for improving adhesion (bufferlayer) 101. The third substrate 117 make it easier to keep strengthafter removing the second substrate 115, handling, or mounting, and thethird substrate 117 is used for protecting the layer 104 including anelement.

Adhesion of the second adhesive 148 is strong with nomal state, and itis preferable that the first adhesive 114 has a property such that theadhesion becomes weak by light irradiation or heating. Specifically, aUV peelable adhesive of which the adhesion becomes weak by irradiationwith ultraviolet radiation, or a heat peelable adhesive of which theadhesion becomes weak by heating may be used. In addition, an adhesiveof which the adhesion becomes weak by a mechanism (heat peeling, UVpeeling), temperature, wave length, or light irradiating direction whichis different from the first adhesive 114 is preferable as the secondadhesive 148, and the combination which can peel off the secondsubstrate which is bonded with the third substrate is used. In thisexample, an adhesive having a heat peeling property is used.

Here, a laminated body having the insulating film 112, the layer 104including an element, and the layer which mainly contains DLC (the layerfor improving adhesion (buffer layer) 101, the DLC layer 102, and thelayer for improving adhesion (buffer layer) 103) may be separated so asto be asigned to every TFT circuit 105 formed in the layer 104 includingan element from the second substrate 115 side. Alternatively, the thirdsubstrate is also divided, and then each of TFT circuits 105 formed inthe layer including an element 104 may be completely divided. In thisexample, dividing is not performed at this time. First, the process ofremoving the second substrate is performed.

Subsequently, a process for reducing adhesion of the first adhesive 114is performed (see FIG. 3B). In this case, UV irradiation is conducted.In a case of a combination of the first substrate to the third substratein which UV radiation does not reach an adhesive even if UV radiation isapplied from either a top surface or a bottom surface (if the firstsubstrate is removed, it is a combination of the second substrate andthe third substrate), UV radiation is applied from a side surface, andthe adhesive is peeled off. If only the third substrate 117 does nottransmit UV radiation, first, UV radiation is applied from the side ofthe first substrate 100 to weaken adhesion, and then the third substrateis bonded. If the first adhesive 114 has a heat peeling property,heating is performed in such a way that the third substrate does notpeel off. If the third substrate is not removed after mouting, anyadhesive can be used as the second adhesive.

Consequently, adhesion of the first adhesive 114 becomes weak, alaminated body having the insulating film 112, the layer 104 includingan element, the layer which mainly contains DLC (the layer for improvingadhesion (buffer layer) 101, the DLC layer 102, and the layer forimproving adhesion (buffer layer) 103), the second adhesive 148, and thethird substrate 117 (the first substrate 100 may be included) can beseparated from the second substrate 115 by a physical means. Then, thesecond substrate 115 is removed (see FIG. 3C).

Subsequently, a laminated body having the insulating film 112, the layer104 including an element, the layer which mainly contains DLC (the layerfor improving adhesion (buffer layer) 101, the DLC layer 102, and thelayer for improving adhesion (buffer layer) 103), the second adhesive148, and the third substrate 117 (the first substrate 100 may beincluded) is cut by a cutting means (see FIG. 4A). In this case, thelaminated body is cut to be separated for every TFT circuit 105 formedin the layer 104 including an element. FIG. 4A shows an example ofcutting using a laser as a cutting means. Note that a cutting meanscorresponds to a laser, a dicer, a wire saw, or a scriber.

After a cutting process, a plurality of integrated circuit devices 118to 120 which have structures shown in FIG. 4B are formed (see FIG. 4B).Since the electrodes 113 are exposed in the integrated circuit devices118 to 120, the integrated circuit devices 118 to 120 can be connectedelectrically with an external portion by the electrodes 113.

Then, the integrated circuit devices 118 to 120 are mounted over othersubstrates severally. In this example, a semiconductor device which cantransmit and receive data without contact (it is referred to as an RFID(Radio Frequency Identification), an ID tag, an IC tag, an IC chip, anRF (Radio Frequency) tag, a wireless tag, an electronic tag, or awireless chip) is assumed, and the integrated circuit devicemanufactured in the above process is mounted on a substrate providedwith an antenna (see. FIG. 5A). A conductive pattern 123 which functionsas an antenna is formed on a forth substrate 122. In this example, ananisotropic conductive paste (ACP) is used to a connecting portion. TheTFT circuit 105 and the conductive pattern 123 which functions as anantenna are electrically connected through via conductive particles, andthe integrated circuit device is bonded to the antenna with an adhesiveresin paste 124. In addition, a method of an anisotropic conductive film(ACF), a non-conductive paste (NCP), solder, or the like may be used forthe mounting.

In this example, an integrated circuit device is mounted over the forthsubstrate 122 provided with an antenna; however, the integrated circuitdevice of the present invention may be mounted over a substrate providedwith an element or a plurality of elements instead of an antenna. Anelement corresponds to a thin film transistor, a capacitor element, aresistance element, an inductor, or a diode.

At this time, mounting can be performed stably, and the layer 104including an element and the electrode 113 can be protected from aphysical breakage by existing the third substrate 117.

In this example, the third substrate 117 is removed afterwards. If thesecond adhesive 148 has a heat peeling property, the third substrate 117is removed by heat treatment (see FIG. 5A). FIG 5B shows a state inwhich the third substrate 117 is removed. In FIG 5A, the third substrate117 is removed; however, it may be finished without removing it.

Thereafter, sealing of one surface of a film is performed by using afirst film 127 in order to improve a water-resistant barrier property,chemical resistance, salt water resistance, scratch resistance, or thelike (see FIGS. 6A and 24B). The first film 127 has an adhesive layer132 in the surface. FIGS. 6A and 6B show the case where the first film127 is sealed after removing the third substrate, and FIGS. 24A and 24Bshow the case where the first film 127 is sealed without removing thethird substrate. There is a case where a process is finished as thisshape, or an RFID is attached with an adhesive like a sticker.

FIGS. 6A and 24A show film sealing on one surface; however, bothsurfaces may be sealed by using a first film 130 and a second film 128as shown in FIGS. 6B and 24B. Sealing of both surfaces may be performedfor each surface separately or by sealing both surfaces at the sametime. An adhesive layers 131 and 129 are formed on the surfaces of afirst film 130 and a second film 128 respectively.

In a semiconductor device which is completed through the above process(in this case, an RFID), the thickness is thin, and lightweight. Inaddition, since the semiconductor device is thin, if the semiconductordevice (RFID) is mounted on goods, the design property is not degraded.Further, the semiconductor device (RFID) can be bonded to any kind ofcurved surface along the curve surface. For example, when thesemidconductor device (RFID) is put through a copying machine or thelike, a chip or a chip connection portion is not damaged, and when thesemiconductor device (RFID) is mounted on a pen, a circular shape of apen can be kept.

A plurality of integrated circuit devices are manufactured by a methodexplained in this embodiment mode, and bonding a plurality of integratedcircuit devices merely with an adhesive repeatedly so that the pluralityof integrated circuit devices are laminated, or bonding is repeated in astate in which electrical connection can be performed thereby laminatingthem. Thus, the integrated circuit device can have a laminated structurehaving two or more layers. Consequently, a multifunctional element canbe formed in a small space. The elements which are included in eachintegrated circuit device may b operated in synchronization byelectricity, magnetism, light, acoustics, vibration, or the like betweenthe bonded integrate circuit devices.

In this embodiment mode described above, an example of forming a layerwhich mainly contains diamond like carbon is formed as a stopper layeris shown. When a DLC layer is used as a stopper layer as in thisembodiment mode, heating conditions of an element formed over the DLClayer are not limited by heat resistance of diamond like carbon.However, a material used as a stopper layer is not limited to DLC. Aslong as a material used as a stopper layer has higher hardness than thefirst substrate 100, the material is not limited. For example, TiCN(titanium carbonitride), TiAlN (titanium aluminum nitride), or the likehaving high hardness can be used. In particular, since TiCN has not onlyhigh hardness but also low coefficient of friction, TiCN is suitable.

In addition, as a stopper layer, a material which has higher hardnessand lower coefficient of friction than the first layer 100 ispreferable.

Layers for improving adhesion (buffer layers) 101 and 103 are notlimited to the materials given in this embodiment mode. The layer forimproving adhesion (buffer layer) 101 may be formed with a material ofwhich adhesion with a substrate is good, and adhesion with a stopperlayer is good. In addition, the layer for improving adhesion (bufferlayer) 103 may be formed with a material of which adhesion with astopper layer is good, and adhesion with a layer including an element isgood.

Embodiment Mode 2

This embodiment mode is described using FIGS. 7A to 10. In thisembodiment mode, an example in which a layer which mainly containsdiamond like carbon is formed over a substrate as a stopper layer in acase that a substrate is made thinly or removed by etching by chemicalreaction is described.

A layer for improving adhesion (buffer layer) 201, a DLC layer 202, anda layer for improving adhesion (buffer layer) 203 are formed in orderover one surface of a first substrate 200.

Next, a layer including an element 204 is formed over the layer forimproving adhesion (buffer layer) 203 (see FIG. 7B). For example, thislayer may have a wire, a capacitor, an inductor (antenna) or the like,and the combination thereof instead of a unit circuit such as a TFTcircuit. In this particular example, a TFT circuit 205 is formed in thelayer including an element 204. In this figure, the TFT circuit 205 hasan N-channel transistor 206 and a P-channel transistor 207. Each of theN-channel transistor 206 and the P-channel transistor 207 has asemiconductor film 208, a gate insulating film 209, a gate electrode210, an interlayer insulating film 211, and a source or drain electrode235.

In this example, a terminal for external connection is formed and theTFT circuit 205 which can be combined with other substrate is formed.Therefore, an insulating film 212 is formed over the layer including anelement 204, and an opening portion is formed in the insulating film212. Next, an electrode 213 enabling contact with the TFT circuit 205 isformed (see FIG. 7C).

Next, a second substrate 215 is bonded over the insulating film 212 andthe electrode 213 by using a first adhesive 214 (see FIG. 8A). Thesecond substrate 215 is a substrate for keeping flatness of the layerincluding an element 204 and for protecting flatness of the layerincluding an element 204. Adhesion of the first adhesive 214 is strongin a nomal state, and it is preferable that the first adhesive 214 has aproperty such that the adhesion becomes weak by light irradiation orheating. Specifically, a UV peelable adhesive of which the adhesionbecomes weak by irradiation with ultraviolet radiation, or a heatpeelable adhesive of which the adhesion becomes weak by heating may beused. In this example, a UV peelable adhesive is used as the firstadhesive 214.

In grinding, polishing, or the like, an elastic substrate (for example,an expand film, or the like) is further bonded over the second substrate215, and a space between separated substrates is made wider by expandingthe elastic substrate after separating the second substrate 215, and thesubstrate can be handled easily. Accordingly, such a method can beemployed. Since an object of this example is to make the first substratethinner by using flatness of the second substrate; therefore, such amethod is not used.

The preceding process may be performed similarly to Embodiment Mode 1.

Next, an etchant resistant layer 216 is formed at least on a sideportion of the first substrate to prevent that etching by chemicalreaction performed in a later process reaching a region other than thefirst substrate (see FIG. 8A). An organic resin may be used as theetchant resistant layer. FIG. 8A shows a case where the etchantresisting layer 216 is formed on a side portion of laminated body havingthe first substrate, the layer for improving adhesion (buffer layer)201, the DLC layer 202, the layer for improving adhesion (buffer layer)203, the layer including an element 204, the insulating film 212, thefirst adhesive 214, and the second substrate 215. When the secondsubstrate does not have resistance to etching by chemical reaction, theetchant resistant layer 216 is formed so as to cover not only the sideportion but also the surface of the second substrate. The etchantresistant layer 216 is formed with a material having resistance to anetchant used for etching by chemical reaction in a later process.

A surface opposite to one surface of the first substrate 200 (a surfaceformed in the TFT circuit 205) is etched by chemical reaction (see FIG.8B). At the minimum etching may be performed until the thickness is suchthat separation becomes easy; however, if the substrate is made thinnerin comparison with before, the thickness is set at 100 μm or less. Whenthe thickness becomes 20 μm or less, the substrate becomes able towithstand bending, so not only thinning but also an advantage offlexibility (an advantage of being able to assume a thing hasflexibility) is expressed, so this is preferable. In a case where aninsulating substrate is used, since an advantage of thinning is largewhen the thickness of the substrate is 10 μm or less, where dependencyof variation in thickness becomes large is big in a semiconductorsubstrate or a conductive substrate, it is even more preferable. In thesemiconductor substrate or the conductive substrate, it is preferable toetch until the first substrate 200 disappears completely; however, whenan element is formed in the substrate, it is preferable that thethickness is in a range of 10 to 100 μm.

When the first substrate 200 is a glass substrate or a quartz substratefor example, HF or ClF₃ is used as an etchant. In addition, for example,when the first substrate 200 is an Si substrate, alkali such as TMAH(tetramethylammonium hydroxide) or halogen gas such as ClF₃ is used asan etchant. When a substrate is a metal substrate, acid or alkali isused. DLC has strong resistance to alkali, HF, and ClF₃. Therefore, evenif etching is performed until the first substrate 200 disappears,further progress of the etching can be prevented by the existence of thelayer for improving adhesion (buffer layer) 201, the DLC layer 202, andthe layer for improving adhesion (buffer layer) 203.

It is known that amorphous carbon has weaker strength than DLC; however,it is known that it has strong resistance chemicals. Therefore, whenetching by chemical reaction is used as a method to thin the firstsubstrate, a layer mainly containing amorphous carbon may be formedinstead of forming a layer mainly containing DLC when the layer forimproving adhesion (buffer layer) 201, the DLC layer 202, and the layerfor improving adhesion (buffer layer) 203 are formed. On that occasion,a Si concentration of the layer for improving adhesion (buffer layer)201 and the layer for improving adhesion (buffer layer) 203 may be therange of 1 to 20%.

After this process is finished, the first substrate may be removedentirely. In this example, the first substrate is removed entirely.

Anyone of a liquid, gas, or plasma can be used as an etchant by chemicalreaction. Cleaning is often performed as necessary, to prevent decayafter etching.

In addition, after grinding or polishing as in Embodiment Mode 1,etching by chemical reaction is used, or after etching by chemicalreaction, grinding or polishing is performed as in Embodiment Mode 1.The combination thereof may be freely used.

In this example, the electrode 213 electrically connected with the TFTcircuit 205 is formed on the second substrate 215 side. In addition, theelectrode can be electrically connected with the TFT circuit 205 on thefirst substrate 200 side, and mounted on another substrate (for example,a substrate on which formed an antenna is formed, or the like). In thiscase, the third substrate below may not necessarily be provided. Amethod for forming the electrode electrically connected with the TFrcircuit 205 on the first substrate 200, in other words, a surface onwhich a DLC layer is existed may be performed similarly to EmbodimentMode 1.

In this example, the integrated circuit is mounted on the secondsubstrate 215 side. If the second substrate 215 is peeled off here, thelayer including an element 204 is curled by stress, and a problem occursin the later mounting or handling. A third substrate 217 is bonded fromthe side opposite to the second substrate 215 by using a second adhesive222 in order to prevent the above problem. In other words, when thefirst substrate 200 remains, the third substrate 217 is bonded to thefirst substrate 200 by using the second adhesive 222. When the firstsubstrate 200 is removed, and the layer for improving adhesion (bufferlayer) 201 is exposed in a surface, the third substrate 217 is bonded tothe layer for improving adhesion (buffer layer) 201 by using the secondadhesive 222. When the first substrate 200 and the layer for improvingadhesion (buffer layer) 201 are removed and the DLC layer 202 is exposedin a surface, the third substrate 217 is bonded to the DLC layer 202 byusing the second adhesive 222 (see FIG. 8C). In this example, since thefirst substrate 200 is removed in FIG. 8C, the third substrate 217 isbonded to the layer for improving adhesion (buffer layer) 201. The thirdsubstrate 217 make it easier to keep strength after removing the secondsubstrate 215, handling, or mounting, and the third substrate 217 isused for protecting the layer including an element 204.

Adhesion of the second adhesive 222 is strong in a nomal state, and itis preferable that the first adhesive 214 has a property such that theadhesion becomes weak by light irradiation or heating. Specifically, aUV peelable adhesive of which the adhesion becomes weak by irradiationwith ultraviolet radiation, or a heat peelable adhesive in which theadhesion becomes weak by heating may be used. In addition, an adhesiveof which adhesion becomes weak by a mechanism (heat peeling, UVpeeling), temperature, wave length, or light irradiating direction whichis different from the first adhesive 214 is preferable as the secondadhesive 222, and the combination which can peel off the secondsubstrate which is bonded with the third substrate is used. In thisexample, an adhesive having a heat peelable property is used.

Here, a laminated body having the insulating film 112, the layerincluding an element 204, and the layer which mainly contains DLC (thelayer for improving adhesion (buffer layer) 201, the DLC layer 202, andthe layer for improving adhesion (buffer layer) 203) may be separated soas to be asigned to every TFT circuit 205 formed in the layer 204including an element from the second substrate 215 side. Alternatively,the third substrate is also divided, and then each of TFT circuits 205formed in the layer including an element 204 may be completely divided.In this example, dividing is not performed at this time. First, theprocess of removing the second substrate is performed.

Subsequently, a process for reducing adhesion of the first adhesive 214is performed (see FIG. 9A). In this case, UV irradiation is conducted.In a case of a combination of the first substrate to the third substratewhere UV radiation does not reach an adhesive even if UV radiation isapplied from either a top surface or a bottom surface (if the firstsubstrate is removed, it is a combination of the second substrate andthe third substrate), UV radiation is applied from a side surface, andthe adhesive is peeled off. If only the third substrate 217 does nottransmit UV radiation, first, UV radiation is applied from the side ofthe first substrate 200 to weaken adhesion, and then the third substrateis bonded. If the first adhesive 214 has a heat peeling property,heating is performed in such a way that the third substrate does notpeel off. If the third substrate is not removed after mouting, anyadhesive can be used as the second adhesive.

Consequently, adhesion of the first adhesive 214 becomes weak, alaminated body having the insulating film 212, the layer including anelement 204, the layer which mainly contains DLC (the layer forimproving adhesion (buffer layer) 201, the DLC layer 202, and the layerfor improving adhesion (buffer layer) 203), the second adhesive 222, andthe third substrate 217 (the first substrate 200 may be included) can beseparated from the second substrate 215 by a physical means. Then, thesecond substrate 215 can be removed. However, since an end portion ofthe second substrate 215 is fixed by the etchant resistant layer 216, atthis point in the process, the second substrate 215 cannot be stillremoved.

Subsequently, a laminated body having the insulating film 212, the layerincluding an element 204, the layer which mainly contains DLC (the layerfor improving adhesion (buffer layer) 201, the DLC layer 202, and thelayer for improving adhesion (buffer layer) 203), the second adhesive222, and the third substrate 217 (the first substrate 200 may beincluded) is cut by a cutting means (see FIG. 9B). In this case, thelaminated body is cut to be separated for every TFT circuit 205 formedin the layer including an element 204. FIG. 9B shows an example ofcutting using a laser as a cutting means. Note that a cutting meanscorresponds to a laser, a dicer, a wire saw, or a scriber. Since the endportion of the second substrate 215 fixed by the etchant resistant layer216 is separated by the above process as shown in FIG. 9B, the secondsubstrate 215 can be removed.

After a cutting process, a plurality of integrated circuit devices 218to 220 which have structures shown in FIG. 10 are formed (see FIG. 10).Since the electrodes 213 are exposed in the integrated circuit devices218 to 220, the integrated circuit devices 218 to 220 can be connectedelectrically with an external portion by the electrodes 213.

A mounting process after that is uses the same process which isdescribed using FIGS. 5A to 6B in Embodiment Mode 1.

In a semiconductor device which is completed through the above process(in this case, an RFID), the thickness is thin, and lightweight. Inaddition, since the semiconductor device is thin, if the semiconductordevice (RFID) is mounted on goods, the design property is not degraded.Further, the semiconductor device (RFID) can be bonded to any kind ofcurved surface along the curve surface. For example, when thesemidconductor device (RFID) is put through a copying machine or thelike, a chip or a chip connection portion is not damaged, and when thesemiconductor device (RFID) is mounted on a pen, a circular shape of apen can be kept.

In this embodiment mode described above, an example of forming a layermainly containing diamond like carbon as a stopper layer is shown. Whena DLC layer is used as a stopper layer as in this embodiment mode,heating conditions of an element formed over the DLC layer are notlimited by heat resistance of diamond like carbon. However, a materialused as a stopper layer is not limited to DLC. As long as a materialused for the stopper layer has a resistance property with respect to anetchant used for etching the first substrate 200, the material used forthe stopper layer is not limited.

Layers for improving adhesion (buffer layers) 201 and 203 are notlimited to the material given in this embodiment mode. The layer forimproving adhesion (buffer layer) 201 may be formed with a material ofwhich adhesion with a substrate is good, and adhesion with a stopperlayer is good. In addition, the layer for improving adhesion (bufferlayer) 203 may be formed with a material of which adhesion with astopper layer is good, and adhesion with a layer including an element isgood.

In addition, in this embodiment mode, a case in which etching bychemical reaction is used when a substrate is thinned or removed isdescribed; however, when a substrate is thinned or removed, etching bychemical reaction can be combined with a grinding or polishing method.In other words, etching by chemical reaction is combined with EmbodimentMode 1. However, when etching by chemical reaction can be combined witha grinding or polishing method as a method for thinning or removing asubstrate, it is necessary to select a material which has a higherdegree of hardness than the first substrate and resistance to theetchant as a stopper layer.

Embodiment Mode 3

This embodiment mode is described using FIGS. 11A to 14C. In thisembodiment mode, a case where a substrate is removed by peeling off thesubstrate by controlling an adhesion property of a DLC layer isdescribed.

A layer for improving adhesion (buffer layer) 301, a DLC layer 302, anda layer for improving adhesion (buffer layer) 303 are formed in orderover one surface of a first substrate 300 (see FIG. 11A).

Next, a layer including an element 304 is formed over the layer forimproving adhesion (buffer layer) 303 (see FIG. 11B). For example, thislayer may have a wire, a capacitor, an inductor (antenna) or the like,and the combination thereof instead of a unit circuit such as a TFTcircuit. In this particular example, a TFT circuit 305 is formed in thelayer including an element 304. In this figure, the TFT circuit 305 hasan N-channel transistor 306 and a P-channel transistor 307. Each of theN-channel transistor 306 and the P-channel transistor 307 has asemiconductor film 308, a gate insulating film 309, a gate electrode310, an interlayer insulating film 311, and a source or drain electrode335.

The preceding process may be performed similarly to Embodiment Mode 1.

Next, an insulating film 312 is formed over the layer including anelement 304, and an opening portion is formed in the insulating film312. Then, an antenna 313 which is contacted with the TFT circuit 305 isformed (see FIG. 11C).

A strength retention layer 314 is formed so as to sandwich the layerincluding an element 304 between the first substrate 300 and thestrength retention layer 314. In this example, a resin film is formed bya screen printing method. And then baked in a oven, thereby forming thestrength retention layer 314 (see FIG. 12A). This layer exists tomaintain the strength of the layer including an element 304 and toprevent a crack or the like enters from occurring when the firstsubstrate 300 is peeled off at a place where the adhesion between thelayer mainly containing DLC and the first substrate 300 is weak, in astep which takes place in a later process.

Next, a second substrate 315 is bonded over the insulating film 312 andthe electrode 313 by using a first adhesive 320 (see FIG. 12B). Thesecond substrate 315 is a substrate for keeping flatness of the layerincluding an element 304 and for protecting flatness of the layerincluding an element 304. Adhesion of the first adhesive 320 is strongin a nomal state, and it is preferable that the first adhesive 320 has aproperty such that the adhesion becomes weak by light irradiation orheating. Specifically, a UV peelable adhesive of which the adhesionbecomes weak by irradiating ultraviolet radiation, or a heat peelingadhesive in which the adhesion becomes weak by heating may be used. Inthis example, a UV peelable adhesive is used as the first adhesive 320.

In grinding, polishing, or the like, an elastic substrate (for example,an expand film, or the like) is further bonded over the second substrate315, and a space between separated substrates is made wider by expandingthe elastic substrate after separating the second substrate 315, and thesubstrates can be handled easily. Accordingly, such a method can beemployed. Since an object of this example is to make the first substratethinner by using flatness of the second substrate; therefore, such amethod is not used. When the second substrate 315 does not haveflexibility, the second substrate becomes flexibile by thinning thesecond substrate 315 by using grinding or polishing of Embodiment Mode 1or etching by chemical reaction of Embodiment Mode 2.

The second substrate 315 side is peeled off by using a physical methodsuch as a roller in which force is applied equally, and the firstsubstrate is removed (see FIG. 12C). This process uses a property inwhich an adhesion property between the layer for improving adhesion(buffer layer) 301 and the first substrate 300 is the weakest inadhesion of the DLC layer which is a three-layer structure in thisexample. Depending on the relative relation of adhesion of the layer forimproving adhesion (buffer layer) 301, the DLC layer 302, and the layerfor improving adhesion (buffer layer) 303, it is possible to peel offthe first substrate from any one of the layer for improving adhesion(buffer layer) 301, the DLC layer 302, or the layer for improvingadhesion (buffer layer) 303 which contains which mainly contains DLC.There is variation in a layer peeled off in a surface of the substrate.However, it is preferable that the layer for improving adhesion (bufferlayer) 301 which is in contact with the layer including an element 304is left, and a DLC coat is maintained under the layer 304 including anelement.

After this process is finished, all of the first substrate 300 isremoved (see FIG. 13A).

In this example, the electrode 313 electrically connected with the TFTcircuit 305 is formed on the second substrate 315 side. In addition, theelectrode can be electrically connected with the TFT circuit 305 on thefirst substrate 300 side, and mounted to another substrate (for example,a substrate on which an antenna is formed, or the like). In this case,the third substrate below may not necessarily be provided. A method toform the electrode electrically connected with the TFT circuit 305 inthe first substrate 300, in other words, a surface in which a DLC layeris existed, is performed similarly to Embodiment Mode 1.

In this example, the integrated circuit is mounted on the secondsubstrate 315 side. If the second substrate 315 is peeled off here, thelayer including an element 304 is curled by stress, and a problem occursin the later mounting or handling. A third substrate 316 is bonded fromthe side opposite to the second substrate 315 by using a second adhesive321 in order to prevent the above problem (see FIG. 13B). In thisexample, since the layer for improving adhesion (buffer layer) 301 isexposed in a surface, the third substrate 316 is bonded to the layer forimproving adhesion (buffer layer) 301 by using the second adhesive 321.The third substrate 316 make it easier to keep strength of afterremoving the second substrate 315, handling, or mounting, and the thirdsubstrate 316 is used for protecting the layer including an element 304.In a case that the strength retention layer 314 has enough strength forstrength retention after peeling off the second substrate 315 or whenhandling or mounting is performed, the third substrate below is notnecessary.

Adhesion of the second adhesive 321 is strong in a nomal state, and itis preferable that a property such that the adhesion becomes weak bylight irradiation or heating. Specifically, a UV peelable adhesive ofwhich the adhesion becomes weak by irradiation with ultravioletradiation, or a heat peelable adhesive of which the adhesion becomesweak by heating may be used. In addition, an adhesive of which theadhesion becomes weak by a mechanism (heat peeling, UV peeling),temperature, wave length, or light irradiating direction which isdifferent from the first adhesive 320 is preferable as the secondadhesive 321, and the combination which can peel off the secondsubstrate which is bonded with the third substrate is used. In thisexample, an adhesive having a heat peeling property is used.

Here, a laminated body having the insulating film 312, the secondsubstrate 315, the first adhesive 320, the strength retention layer 314,the insulating film 312, the layer including an element 304, and thelayer which mainly contains DLC (the layer for improving adhesion(buffer layer) 301, the DLC layer 302, and the layer for improvingadhesion (buffer layer) 303) may be separated so as to be asigned toevery TFT circuit 305 formed in the layer including an element 304 fromthe second substrate 315 side. Alternatively, the third substrate 316 isalso divided, and then each of TFT circuits 305 formed in the layerincluding an element 304 may be completely divided. In this example,dividing is not performed at this time. First, the process of removingthe second substrate is performed.

Subsequently, a process for reducing adhesion of the first adhesive 320is performed (see FIG. 13C). In this case, UV irradiation is conducted.In a case of a combination of the first substrate to the third substratewhere UV radiation does not reach an adhesive even if UV radiation isapplied from either a top surface or a bottom surface (if the firstsubstrate is removed, it is a combination of the second substrate andthe third substrate), UV radiation is applied from a side surface, andthe adhesive is peeled off. If only the third substrate 316 does nottransmit UV radiation, first, UV radiation is applied from the side ofthe first substrate 300 to weaken adhesion, and then the third substrateis bonded. If the first adhesive 320 has a heat peeling property,heating is performed in such a way that the third substrate does notpeel off. If the third substrate is not removed after mouting, anyadhesive can be used as the second adhesive.

Concequently, adhesion of the first adhesive 320 becomes weak, alaminated body having the strength retention layer 314, the insulatingfilm 312, the layer including an element 304, the first adhesive 320,the layer which mainly contains DLC (the layer for improving adhesion(buffer layer) 301, the DLC layer 302, and the layer for improvingadhesion (buffer layer) 303), the second adhesive 321, and the thirdsubstrate 316 (the first substrate 300 may be included) can be separatedfrom the second substrate 315 by a physical means. Then, the secondsubstrate 315 can be removed (see FIG. 14A).

Subsequently, a laminated body having the strength retention layer 314,the insulating film 312, the layer including an element 304, the firstadhesive 320, the layer which mainly contains DLC (the layer forimproving adhesion (buffer layer) 301, the DLC layer 302, and the layerfor improving adhesion (buffer layer) 303), the second adhesive 321, andthe third substrate 316 (the first substrate 300 may be included) is cutby a cutting means (see FIG. 14B). In this case, the laminated body iscut to be separated for every TFT circuit 305 formed in the layerincluding an element 304. FIG. 14B shows an example of cutting using alaser as a cutting means. Note that a cutting means corresponds to alaser, a dicer, a wire saw, or a scriber.

After a cutting process, a plurality of integrated circuit devices 317to 319 which have structures shown in FIG. 14C are formed (see FIG.14C).

Subsequently, each of the integrated circuits is sealed with a filmhaving an adhesive layer on the surface. A film used for sealing may bethe same as the film used for sealing in Embodiment Mode 1.

In a semiconductor device which is completed through the above process(in this case, an RFID), the thickness is thin, and lightweight. Inaddition, since the semiconductor device is thin, if the semiconductordevice (RFID) is mounted on goods, the design property is not degraded.Further, the semiconductor device (RFID) can be bonded to any kind ofcurved surface along the curve surface. For example, when thesemidconductor device (RFID) is put through a copying machine or thelike, a chip or a chip connection portion is not damaged, and when thesemiconductor device (RFID) is mounted on a pen, a circular shape of apen can be kept.

If the manufacturing method of the integrated circuit device describedin this embodiment mode is used, heat treatment can be performed withoutproviding a significant change in adhesion due to heat resistance ofDLC. Therefore, there is a merit that limitations on process are reducedin manufacturing a thin integrated circuit device.

Layers for improving adhesion (buffer layers) 301 and 303 are notlimited to the material given in this embodiment mode. The layer forimproving adhesion (buffer layer) 301 may be formed with a material ofwhich adhesion with a substrate is good, and adhesion with a stopperlayer is good. In addition, the layer for improving adhesion (bufferlayer) 303 may be formed with a material of which adhesion with astopper layer is good, and adhesion with a layer including an element isgood.

This embodiment mode describes the case that peeling off of thesubstrate by controlling an adhesion property of the DLC layer is usedwhen the substrate is thinned or removed; however, when a substrate isthinned or removed, peeling off the substrate can be combined withgrinding or polishing, or etching by chemical reaction. Therefore, thisembodiment mode can be combined with Embodiment Mode 1 or 2.

By combining an adhesion controlling method with a method of grinding orpolishing, in the process of grinding or polishing, a substrate ispeeled off by shock of grinding or polishing, and the substrate can beremoved. In addition, in a case that a method of grinding or polishingis combined with an adhesion controlling method, and when etching bychemical reaction method is combined with an adhesion controllingmethod, even if the substrate is thinned to a degree of havingflexibility by a grinding or a polishing method, or etching by chemicalreaction method, even in the case of forming an integrated circuit overthe substrate that is originally hard, since the substrate becomes thinto have flexibility, the substrate can be removed while curving thesubstrate.

Embodiment Mode 4

This embodiment mode is described by using FIGS. 15A to 19. In thisembodiment mode, an example in which a layer which mainly contains DLCis formed over a substrate as a stopper layer when the substrate isthinned by grinding or polishing is described. In this embodiment mode,the case that a wireless device which is not in contact with an externalportion is manufactured is described.

A layer for improving adhesion (buffer layer) 401, a DLC layer 402, anda layer for improving adhesion (buffer layer) 403 are formed in orderover one surface of a first substrate 400 (see FIG. 15A).

Next, a layer including an element 404 is formed over the layer forimproving adhesion (buffer layer) 403 (see FIG. 15B). This layer mayhave a wire, a capacitor, an inductor (antenna) or the like, and thecombination thereof instead of a unit circuit such as a TFT circuit. Inthis particular example, a TFT circuit 405 is formed in the layerincluding an element 404. In this figure, the TFT circuit 405 has anN-channel transistor 406 and a P-channel transistor 407. Each of theN-channel transistor 406 and the P-channel transistor 407 has asemiconductor film 408, a gate insulating film 409, a gate electrode410, an interlayer insulating film 411, and a source or drain electrode435.

The preceding process may be performed similarly to Embodiment Mode 1.

In this example, an integrated circuit device used without connectingwith an external portion is manufactured. In this example, an integratedcircuit device which communicates by using an antenna is manufactured(see FIG. 15C). In this example, an example of an integrated circuitdevice which communicates by using an antenna is described; however, anycommunication metho such as an antenna which communicates by usingelectromagnetic wave, light, magnetism, electric potential, acoustics,physical switch, or the like is not limited. An internal sensor, adisplay portion showing memory data, a vibrator, a speaker, or the likemay be used. On this occation, an insulating film 412 is formed over thelayer including an element 404, and an opening portion is formed in theinsulating film 412. Next, an antenna 413 which is electricallyconnected with the TFT circuit 405 is formed.

A layer which mainly contains DLC is formed thereover. Specifically, alayer for improving adhesion (buffer layer) 431 and a DLC layer 432 areformed (see FIG. 16A). Further, a layer for improving adhesion (bufferlayer) may be formed thereover, and a three-layer structure may beformed; however, since an adhesion property is not all that necessary ina later process, two-layer structure is used in this example. DLC isformed front and rear surfaces, and an integrated circuit device whichis superior to a gas barrier property or the like can be manufactured.

When all of elements are covered with DLC, a gas barrier property bycoating with DLC obtains the biggest effect. After etching each regionbetween TFTs 405 formed in the layer including an element 404 to thelayer which mainly contains DLC (the layer for improving adhesion(buffer layer) 401, the DLC layer 402 the layer for improving adhesion(buffer layer) 403) as shown in FIG. 20A before forming a layer whichmainly contains DLC (a layer for improving adhesion (buffer layer) 431and a DLC layer 432) in FIG. 16A, if each TFT 405 is divided, each TFT405 is wrapped with DLC by forming a layer which mainly contains DLC (alayer for improving adhesion (buffer layer) 431 and a DLC layer 432) asshown in FIG. 20B. In this state, since DLC has a strong chemical proofproperty, there is a case that an etchant resistant layer is notnecessary when the substrate is thinned or removed by etching bychemical reaction in a process of manufacturing an integrated circuitdevice which has a structure of covering the TFT circuit 405 with DLC bythe method described in Embodiment Mode 2, or the like. An after processis similarly to a case forming the DLC layer at a front or a rear side.

Next, a second substrate 415 is bonded over the DLC layer 432 by using afirst adhesive 414 (see FIGS. 16B and 20C). The second substrate 415 isa substrate for keeping flatness of the layer including an element 404and for protecting flatness of the layer including an element 404.Adhesion of the first adhesive 414 is strong in a nomal state, and it ispreferable that the first adhesive 414 has a property such that theadhesion becomes weak by light irradiation or heating. Specifically, aUV peelable adhesive in which the adhesion becomes weak by irradiationwith ultraviolet radiation, or a heat peelable adhesive of which theadhesion becomes weak by heating may be used. In this example, a UVpeelable adhesive is used as the first adhesive 414.

In grinding, polishing, or the like, an elastic substrate (for example,an expand film, or the like) is further bonded over the second substrate415, and a space between separated substrates is made wider by expandingthe elastic substrate after separating the second substrate 415, and thesubstrates can be handled easily. Accordingly, such a method can beemployed. Since an object of this example is to make the first substratethinner by using flatness of the second substrate 415; therefore, inthis example, such a method is not used.

Next, a surface opposite to one surface (a surface over which in the TFTcircuit 405 is formed) of the first substrate 400 is ground or polishedby a grinding means or a polishing means (see FIGS. 16C and 21A). Inthis example, grinding is performed until a thickness of the firstsubstrate 400 becomes 100 μm or less. Then, polishing is performed untilthe thickness of the first substrate 400 becomes 20 μm or less.

Here, an example in which the first substrate 400 is ground until thethickness becomes 100 μm or less, and then, the first substrate 400 ispolished until the thickness becomes 20 μm or less is shown; however,grinding or polishing may be performed at least until the thickness ofthe first substrate 400 becomes thin to be easily separated. If thesubstrate is made thinner than before, the thickness should be 100 μm orless. Since the substrate becomes strong against bending when thethickness becomes 20 μm or less, the substrate can be made not only thinbut also flexible (an advantage which can be assumed a thing havingflexibility), which is preferable. In a case of using an insulatingsubstrate, since an advantage of thinning is significant when thethickness of the substrate is 10 μm or less where dependency ofvariations in the thickness is considerable a semiconductor substrate ora conductive substrate, it is more preferable. In the semiconductorsubstrate or the conductive substrate, it is preferable to remove thesubstrate completely; however, when an element is formed in thesubstrate, the thickness of the substrate is in the range of 10 to 100μm.

In this grinding process, the surface of the first substrate 400 isground or polished by rotating one or both a stage on which the firstsubstrate is fixed and of the grinding means or the polishing means 417.At this time, not only the first substrate 400 but also the secondsubstrate 415 may be ground or polished at the same time. This exampleshows a case where only the first substrate 400 is ground or polished.

The grinding means or the polishing means 417 is, for example, agrinding stone used for grinding or loose abrasive process graintreatment used for polishing. Thereafter, cleaning may be performed asnecessary in order to remove dust generated by a grinding or a polishingprocess.

After this process is finished, the first substrate 400 may be removedentirely (see FIGS. 17A and 21B). FIGS. 17A and 21B show a case that thefirst substrate is removed entirely.

In addition, when the first substrate is thinned by using a grindingmeans or a polishing means, the first substrate 400 may be peeled offfrom the layer for improving adhesion (buffer layer) 401 by shock andvibration of grinding or polishing. Controlling of the adhesion isdescribed in detail in Embodiment Mode 3.

In this example, mounting on another substrate is not performed;however, after covering with DLC, contact can be performed from a frontlayer or a rear layer. In a case that mounting is performed on a side ofthe first substrate 400 or the layer which mainly contains DLC (thelayer for improving adhesion (buffer layer) 401, the DLC layer 402, thelayer for improving adhesion (buffer layer) 403), the method describedin Embodiment Mode 1 is used.

If the second substrate 415 is peeled off here, the layer including anelement 404 is curled by stress, and a problem occurs in the latermounting or handling. A third substrate 428 is bonded from the sideopposite of the second substrate 415 by using a second adhesive 427 inorder to prevent the above problem. In other words, at this time, whenthe first substrate 400 remains, the third substrate 428 is bonded tothe first substrate 400 by using the second adhesive 427. When the firstsubstrate 400 is removed, and the layer for improving adhesion (bufferlayer) 401 is exposed in a surface, the third substrate 428 is bonded tothe layer for improving adhesion (buffer layer) 401 by using the secondadhesive 427. When the first substrate 400 and the layer for improvingadhesion (buffer layer) 401 are removed and the DLC layer 402 is exposedin a surface, the third substrate 428 is bonded to the DLC layer 402 byusing the second adhesive 427 (see FIGS. 17B and 21C). In this example,the third substrate 428 is bonded to the layer for improving adhesion(buffer layer) 401. The third substrate 428 makes it easier to keepstrength after removing the second substrate 415, handling, or mounting,and the third substrate 428 is used for protecting the layer includingan element 404.

Adhesion of the second adhesive 427 is strong in a nomal state, and itis preferable that the first adhesive 414 has a property such that theadhesion becomes weak by light irradiation or heating. Specifically, aUV peelable adhesive of which the adhesion becomes weak by irradiationwith ultraviolet radiation, or a heat peelable adhesive of which theadhesion becomes weak by heating may be used. In addition, an adhesiveof which the adhesion becomes weak by a mechanism (heat peeling, UVpeeling), temperature, wave length, or light irradiating direction whichis different from the first adhesive 414 is preferable as the secondadhesive 427, and the combination which can peel off the secondsubstrate which is bonded with the third substrate 428 is used. In thisexample, an adhesive having a heat peeling property is used as thesecond adhesive 427.

Here, a laminated body having the second substrate 415, the firstadhesive 414, the layer which mainly contains DLC (the layer forimproving adhesion (buffer layer) 431, the DLC layer 432), theinsulating film 412, the layer including and element 404, the layerwhich mainly contains DLC (the layer for improving adhesion (bufferlayer) 401, the DLC layer 402, and the layer for improving adhesion(buffer layer) 403) may be separated so as to be assigned to every TFTcircuit 205 formed in the layer including an element 404 from the secondsubstrate 415 side. Alternatively, the third substrate is also divided,and then each of TFT circuits 405 formed in the layer including anelement 404 may be completely divided. In this example, dividing is notperformed at this time. First, the process of removing the secondsubstrate is performed.

Subsequently, a process for reducing adhesion of the first adhesive 414is performed (see FIGS. 17C and 22A). In this case, UV irradiation isconducted. In a case of a combination of the first substrate to thethird substrate 428 where UV radiation does not reach an adhesive evenif UV radiation is applied from either a top surface or a bottom surface(if the first substrate is removed, it is a combination of the secondsubstrate and the third substrate), UV radiation is applied from a sidesurface, and the adhesive is peeled off. If only the third substrate 428does not transmit UV radiation, first, UV radiation is applied from theside of the first substrate 400 to weaken adhesion, and then the thirdsubstrate is bonded. If the first adhesive 414 has a heat peelingproperty, heating is performed in such a way that the third substratedoes not peel off. If the third substrate is not removed after mouting,any adhesive can be used as the second adhesive.

Concequently, adhesion of the first adhesive 414 becomes weak, alaminated body having the layer which mainly contains DLC (the layer forimproving adhesion (buffer layer) 431, the DLC layer 432), theinsulating film 412, the layer including an element 404, the layer whichmainly contains DLC (the layer for improving adhesion (buffer layer)401, the DLC layer 402, and the layer for improving adhesion (bufferlayer) 403), the second adhesive 427, and the third substrate 428 (thefirst substrate 400 may be included) can be separated from the secondsubstrate 415 by a physical means. Then, the second substrate 415 can beremoved (see FIGS. 18A and 22B).

Subsequently, a laminated body having the layer which mainly containsDLC (the layer for improving adhesion (buffer layer) 431, the DLC layer432), the insulating film 412, the layer including an element 404, thelayer which mainly contains DLC (the layer for improving adhesion(buffer layer) 401, the DLC layer 402, and the layer for improvingadhesion (buffer layer) 403), the second adhesive 427, and the thirdsubstrate 428 (the first substrate 400 may be included) is cut by acutting means (see FIGS. 18B and 22C). In this case, each of the layerwhich mainly contains DLC (the layer for improving adhesion (bufferlayer) 431, the DLC layer 432), the insulating film 412, the layerincluding an element 404, the layer which mainly contains DLC (the layerfor improving adhesion (buffer layer) 401, the DLC layer 402, and thelayer for improving adhesion (buffer layer) 403), and the TFT circuit405 formed in the layer including an element 404 is cut to be separated.FIGS. 18B and 22C show an example of cutting using a laser as a cuttingmeans. Note that a cutting means corresponds to a laser, a dicer, a wiresaw, or a scriber.

After a cutting process, a plurality of integrated circuit devices 419to 421 which have structures shown in FIGS. 18C and 23A are formed (seeFIGS. 18C and 23A).

In this example, the third substrate 428 is not removed thereafter, andboth sides of the integrated circuit device are sealed with a first film423 and a second film 424 (see FIGS. 19 and 23B). Adhesive layers 426and 429 are formed on the surface of the first film 423 and the secondfilm 424 respectively. Sealing of both surfaces may be performedseparately for each surface or both surfaces at the same time.

If adhesion of the second adhesive 427 can be lowered, sealing may beperformed after removing the third substrate 428. For example, if anadhesive of which adhesion force is weakened by heating is used as thesecond adhesive 427, the third substrate 428 can be removed by heatingtreatment. Sealing of both surfaces may be performed separately or atthe same time; however, when curl of the integrated circuit device isconsidered, it is preferable that a surface opposite to the thirdsubstrate is sealed with the first film 423 while leaving the thirdsubstrate 428, and after peeling off the third substrate, sealing isperformed with the second film 424.

In a semiconductor device which is completed through the above process(in this case, an RFID), the thickness is thin, and lightweight. Inaddition, since the semiconductor device is thin, if the semiconductordevice (RFID) is mounted on goods, the design property is not degraded.Further, the semiconductor device (RFID) can be bonded to any kind ofcurved surface along the curve surface. For example, when thesemidconductor device (RFID) is put through a copying machine or thelike, a chip or a chip connection portion is not damaged, and when thesemiconductor device (RFID) is mounted on a pen, a circular shape of apen can be kept.

In this embodiment mode described above, an example of forming a layerwhich mainly contains diamond like carbon is formed as a stopper layeris shown. When a DLC layer is used as a stopper layer as in thisembodiment mode, heating conditions of an element formed over the DLClayer are not limited by heat resistance of diamond like carbon.However, a material used as a stopper layer is not limited to DLC. Aslong as the material used for the stopper layer has higher hardness thanthe first substrate 400, it is not limited. For example, since TiCN(titanium carbonitride), TiAlN (titanium aluminum nitride), or the likehaving high hardness can be used. In particular, since TiCN has not onlyhigh hardness but also low coefficient of friction, TiCN is suitable.

In addition, as a stopper layer, a material which has higher hardnessand low coefficient of friction than the first layer 400 is preferable.

Layers for improving adhesion (buffer layers) 401 and 403 are notlimited to the material given in this embodiment mode. The layer forimproving adhesion (buffer layer) 401 may be formed with a material ofwhich adhesion with a substrate is good, and adhesion with a stopperlayer is good. In addition, the layer for improving adhesion (bufferlayer) 203 may be formed with a material of which adhesion with astopper layer is good, and adhesion with a layer including an element isgood.

In addition, in this embodiment mode, an example in which grinding orpolishing is used for thinning or removing the substrate is described;however, peeling off by etching by chemical reaction or controlling anadhesion property of DLC may be used. When the substrate is thinned ofremoved, a method by grinding or polishing can be combined with a methodof etching by chemical reaction, a method by grinding or polishing canbe combined with a method using peeling off by controlling an adhesionproperty of DLC, or a method of etching by chemical reaction can becombined with a method using peeling off by controlling an adhesionproperty of DLC. Therefore, this embodiment mode can be combined withEmbodiment Modes 2 or 3.

As a method of thinning or removing the substrate, when etching bychemical reaction can be combined with a grinding or polishing method asa method for thinning or removing a substrate, it is necessary to selecta material which has a higher degree of hardness than the firstsubstrate and resistance to an etchant as the stopper layer.

Since in the integrated circuit device manufactured by the manufacturingmethod of this embodiment mode, a top or a bottom of the layer includingan element 404 are covered with the DLC layer, or the left, right, topand bottom sides of the layer including an element 404 are all coveredwith the DLC layer, the integrated circuit device is superior in amoisture resistance property and a gas barrier property.

Embodiment 1

The semiconductor device (RFID) of the present invention described inabove embodiment modes can be applied over a wide range and specificexamples of these applications are described hereinafter. Thesemiconductor device 810 of the present invention can be applied to, forexample, a banknote, a coin, documents of value, unregistered bonds,identification certificates (driver's license, certificate of residence,and the like, refer to FIG. 25A), pack cases (a pack paper, a bottle,and the like, refer to FIG. 25B), recording media (DVD software, a videotape, and the like, refer to FIG. 25C), vehicles (a bicycle and thelike, refer to FIG. 25D), personal belongings (a bag, glasses, and thelike (refer to FIG. 25E), foods, clothes, general merchandise,electronic appliances, and the like. The electronic appliances include aliquid crystal display device, an EL display device, a television device(also referred to as simply a TV, a TV receiving machine, or atelevision receiving machine), a mobile phone, and the like.

The semiconductor device 810 (RFID) of the present invention is fixed toan object by mounting the device onto a print substrate, pasting thedevice to the surface, or embedding the device inside the object. Forexample, if the object is a book, the device is fixed to the book byembedding the device inside the paper, and if the object is a packagemade of an organic resin, the device is fixed to the package byembedding the device inside the organic resin. Since the semiconductordevice 810 of the present invention is small, thin, and light-weight,the design quality is not degraded even after the device is fixed to anobject. By providing the semiconductor device 810 of the presentinvention to a banknote, a coin, documents of value, unregistered bonds,identification certificates, and the like, an identification functioncan be provided, thereby preventing the forgery. Moreover, when thesemiconductor device 810 of the present invention is provided in packcases, recording media, personal belongings, foods, clothes, generalmerchandise, electronic appliances, and the like, a system such as aninspection system becomes more efficient.

Subsequently, an example of a system using the semiconductor device(RFID) of the present invention is described. First, a reader/writer 895is provided at a side surface of a mobile terminal including a displayportion 894 and the semiconductor device 896 (RFID) of the presentinvention is provided at a side surface of an object 897 (refer to FIG.26A). In addition, information of the object 897 such as a material, aproduction area, or a history of a circulation process is stored in thesemiconductor device 896 (RFID) in advance. Then, the information in thesemiconductor device 896 (RFID) is displayed in the display portion 894when the semiconductor device 896 (RFID) is held over the reader/writer895. Thus, a useful system can be provided. As another example, thereader/writer 895 is provided beside a belt conveyer (refer to FIG.26B). Then, a system which can inspect the object 897 very easily can beprovided. In this way, by using the semiconductor device (RFID) of thepresent invention for management or a circulation system of objects, thesystem can become more sophisticated and useful.

This application is which mainly contains Japanese Patent Applicationserial No. 2005-164605 filed in Japan Patent Office on Jun. 3, 2005, theentire contents of which are hereby incorporated by reference.

1. A manufacturing method of an integrated circuit device, comprisingthe steps of: forming a first layer which has higher hardness than afirst substrate over one surface of the first substrate; forming abuffer layer over the first layer; forming an element over the bufferlayer; bonding a second substrate over the element; and grinding orpolishing the first substrate from another surface of the firstsubstrate, wherein the element includes a thin film transistor, andwherein a material used as the first layer is selected from titaniumcarbonitride or titanium aluminium nitride.
 2. The manufacturing methodof an integrated circuit device according to claim 1, wherein athickness of the first substrate is 100 μm or less after grinding orpolishing the first substrate.
 3. A manufacturing method of anintegrated circuit device, comprising the steps of: forming a firstlayer over one surface of a first substrate; forming a buffer layer overthe first layer; forming an element over the buffer layer; bonding asecond substrate over the element; and etching the first substrate fromanother surface of the first substrate by chemical reaction, wherein thefirst layer is formed with a material which is resistant to an etchantused for etching the first substrate, wherein the element includes athin film transistor, and wherein the material used as the first layeris selected from titanium carbonitride or titanium aluminium nitride. 4.The manufacturing method of an integrated circuit device according toclaim 3, wherein a thickness of the first substrate is 100 μm or lessafter etching the first substrate.
 5. A manufacturing method of anintegrated circuit device, comprising the steps of: forming a firstlayer which mainly contains diamond like carbon over one surface of afirst substrate; forming a buffer layer over the first layer; forming anelement over the buffer layer; bonding a second substrate over theelement; and thinning the first substrate from another surface of thefirst substrate or removing the first substrate, wherein the elementincludes a thin film transistor, and wherein the buffer layer isselected from a tungsten carbide film, a boron carbonitride film, aboron nitride film or a diamond like carbon film including titanium. 6.The manufacturing method of an integrated circuit device according toclaim 5, wherein the step of thinning the first substrate is performedby grinding or polishing the first substrate.
 7. The manufacturingmethod of an integrated circuit device according to claim 5, wherein thestep of thinning the first substrate is performed by etching the firstsubstrate by chemical reaction.
 8. The manufacturing method of anintegrated circuit device according to claim 5, wherein diamond likecarbon film including nitrogen, a boron carbonitride film, or a tungstencarbide film is formed between the first substrate and the first layer.9. The manufacturing method of an integrated circuit device according toclaim 5, wherein a layer which mainly contains diamond like carbon andSi in a range of 1% to 20% is formed between the first substrate and thefirst layer.
 10. The manufacturing method of an integrated circuitdevice according to claim 5, further comprising the steps of: forming asecond layer which mainly contains diamond like carbon and Si in a rangeof 1% to 20% between the first substrate and the first layer; forming alayer which mainly contains diamond like carbon and Si in a range of 1%to 20% between the first layer and the element, wherein a Siconcentration of the second layer is lower than a Si concentration ofthe layer.
 11. The manufacturing method of an integrated circuit deviceaccording to claim 5, wherein a thickness of the first substrate is 100μm or less after thinning the first substrate.
 12. A manufacturingmethod of an integrated circuit device, comprising the steps of: forminga first layer which mainly contains diamond like carbon over a firstsubstrate; forming a first element over the first layer; forming asecond layer which mainly contains diamond like carbon over a secondsubstrate; forming a second element over the second layer; bonding thefirst substrate with the second substrate so that the first elementfaces the second element; and thinning or removing one or both of thefirst substrate and the second substrate, wherein each of the firstelement and the second element includes a thin film transistor.
 13. Themanufacturing method of an integrated circuit device according to claim12, wherein the first substrate is bonded with the second substrate sothat the first element and the second element are electricallyconnected.
 14. The manufacturing method of an integrated circuit deviceaccording to claim 12, wherein the first substrate and the secondsubstrate are bonded with an adhesive.
 15. The manufacturing method ofan integrated circuit device according to claim 12, wherein a thicknessof the first substrate is in a range of 10 μm to 100 μm after thinningthe first substrate.
 16. A manufacturing method of an integrated circuitdevice, comprising the steps of: forming a first layer which mainlycontains diamond like carbon over one surface of a first substrate;forming a buffer layer over the first layer; forming an element over thebuffer layer; bonding a second substrate over the element using anadhesive; and thinning the first substrate from another surface of thefirst substrate or removing the first substrate, wherein the elementincludes a thin film transistor, and wherein the buffer layer isselected from a tungsten carbide film, a boron carbonitride film, aboron nitride film or a diamond like carbon film including titanium. 17.The manufacturing method of an integrated circuit device according toclaim 16, wherein a thickness of the first substrate is 100 μm or lessafter thinning the first substrate.
 18. A manufacturing method of anintegrated circuit device, comprising the steps of: forming a firstlayer which mainly contains diamond like carbon over a first substrate;forming a buffer layer over the first layer; forming a first elementover the buffer layer; forming a second element over a second substrate;bonding the first substrate with the second substrate so that the firstelement faces the second element; and thinning or removing one or bothof the first substrate and the second substrate, wherein each of thefirst element and the second element includes a thin film transistor,and wherein the buffer layer is selected from a tungsten carbide film, aboron carbonitride film, a boron nitride film or a diamond like carbonfilm including titanium.
 19. The manufacturing method of an integratedcircuit device according to claim 18, wherein the first substrate isbonded with the second substrate so that the first element and thesecond element are electrically connected.
 20. The manufacturing methodof an integrated circuit device according to claim 18, wherein the firstsubstrate and the second substrate are bonded with an adhesive.
 21. Themanufacturing method of an integrated circuit device according to claim18, wherein a thickness of the first substrate is 100 μm or less afterthinning the first substrate.
 22. A manufacturing method of anintegrated circuit device, comprising the steps of: forming a firstlayer which mainly contains diamond like carbon over one surface of afirst substrate; forming a buffer layer over the first layer; forming anelement over the buffer layer; bonding a second substrate over theelement; and thinning the first substrate from another surface of thefirst substrate or removing the first substrate, wherein the elementincludes a thin film transistor, and wherein the buffer layer mainlycontains amorphous carbon.
 23. The manufacturing method of an integratedcircuit device according to claim 22, wherein the step of thinning thefirst substrate is performed by grinding or polishing the firstsubstrate.
 24. The manufacturing method of an integrated circuit deviceaccording to claim 22, wherein the step of thinning the first substrateis performed by etching the first substrate by chemical reaction. 25.The manufacturing method of an integrated circuit device according toclaim 22, wherein diamond like carbon film including nitrogen, a boroncarbonitride film, or a tungsten carbide film is formed between thefirst substrate and the first layer.
 26. The manufacturing method of anintegrated circuit device according to claim 22, wherein a Siconcentration of the buffer layer is in a range of 1% to 20%.
 27. Themanufacturing method of an integrated circuit device according to claim22, further comprising the steps of: forming a second layer which mainlycontains diamond like carbon and Si in a range of 1% to 20% between thefirst substrate and the first layer; and forming a layer which mainlycontains diamond like carbon and Si in a range of 1% to 20% between thefirst layer and the element, wherein a Si concentration of the secondlayer is lower than a Si concentration of the layer.
 28. Themanufacturing method of an integrated circuit device according to claim22, wherein a thickness of the first substrate is 100 μm or less afterthinning the first substrate.